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C++ Programming Code Examples

C++ > Games Code Examples

Graphic Tictactoe - The first ever tictactoe playing artificial intelligence.

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/* Graphic Tictactoe - The first ever tictactoe playing artificial intelligence. None has defeated this computer 'A.I.' . The game is very flexible. Either the user or the 'A.I.' can start the game. User is free to select his own symbol */ #include<iostream.h> #include<conio.h> #include<graphics.h> #include<stdlib.h> #include<string.h> #include<dos.h> void*message; int select(int mult) { union REGS inregs, outregs ; int bli=1,use=1,key=34,i; settextstyle(2,0,5); while(key!=28) { if(bli>0) { use=bli; setfillstyle(1,0); bli=0-bli; } else if(bli<0) { use=0-bli; setfillstyle(1,8); bli=0-bli; } floodfill(221,111+use*40,15); delay(100); if(bli<0) { key=kbhit(); if(kbhit()) { inregs.h.ah = 0 ; int86(22, &inregs, &outregs) ; key=outregs.h.ah; } } if((key==72)&&(use>1)) { bli=use-1; } if((key==80)&&(use<mult)) { bli=use+1; } } if(bli<0) bli=0-bli; return(bli); } void box(char mes[50]) { putimage(5,5,message,0); settextstyle(0,0,1); outtextxy(20,30,mes); } void draw(char mn[3][3]) { char as[3][3][3]; char num[9][3]; for(int i=0;i<10;i++) { strcpy(num[i]," "); num[i][0]=char(49+i); } for(i=0;i<3;i++) for(int j=0;j<3;j++) strcpy(as[i][j]," "); for(i=0;i<3;i++) { for(j=0;j<3;j++) {as[i][j][0]=mn[i][j];} } clearviewport(); setcolor(15); rectangle(0,0,639,479); setfillstyle(1,8); settextstyle(0,0,1); for(i=0;i<3;i++) { rectangle(192,117+i*85,267,192+i*85); outtextxy(260,185+i*85,num[0+i*3]); rectangle(277,117+i*85,352,192+i*85); outtextxy(345,185+i*85,num[1+i*3]); rectangle(362,117+i*85,437,192+i*85); outtextxy(430,185+i*85,num[2+i*3]); } floodfill(500,430,15); setcolor(15); settextstyle(1,0,4); for(i=0;i<3;i++) { outtextxy(221,135+i*85,as[i][0]); outtextxy(306,135+i*85,as[i][1]); outtextxy(391,135+i*85,as[i][2]); } } void main() { clrscr(); int gd=DETECT,gm; initgraph(&gd,&gm,""); message=malloc(imagesize(5,5,634,55)); setcolor(15); rectangle(5,5,634,55); setfillstyle(1,RED); floodfill(30,30,15); outtextxy(10,10,"Message:-"); getimage(5,5,634,55,message); char col[3][3],input,madu,comps,hums,mess[70]={"computer has selected the symbol . Press any key to continue.."}; int exii,dang[8],my[8],hard,many,result,guess=7,bre,mad=2,count=0,dont=0,play[ 8],p,q,end=0,note,inpu,first,use; do {guess=7;mad=2;count=0;dont=0;end=0;result=0; for(int i=0;i<8;i++) play[i]=0; many=0;exii=1; clearviewport(); setcolor(15); rectangle(0,0,639,479); rectangle(20,320,620,460); rectangle(220,150,390,180); rectangle(240,155,370,175); setfillstyle(1,8); floodfill(100,100,15); setcolor(15); settextstyle(4,0,4); outtextxy(200,50,"TIC TAC TOE"); settextstyle(3,0,1); outtextxy(40,290,"How to play :-"); outtextxy(35,330,"In this Game, you may select your symbol. You must try attain"); outtextxy(26,350,"three of your symbols in a line. if you suceed you are the winner."); outtextxy(35,370," But at the same time you should prevent the computer from"); outtextxy(35,390,"getting three of its symbols in a line. To play enter the number"); outtextxy(32,410,"associated with the place where you want to play. Press any key"); outtextxy(35,430,"to start"); settextstyle(2,0,6); outtextxy(258,155,"Start Game"); select(1); hard=2; for(int j=0;j<8;j++) {dang[j]=0;my[j]=0;play[j]=0;} for(j=0;j<3;j++) { for(int k=0;k<3;k++) col[j][k]=' '; } draw(col); box("Please type in your symbol"); hums=getche(); if((hums!='X')&&(hums!='x') ) comps='X'; else comps='0'; mess[33]=comps; box(mess); getch(); randomize(); first=(int(rand()%100)); if(hard==2)guess=(int(rand()%100)); else guess=5; if((first%4)>=2) {use=guess%3;box("Computer has the first chance to play!");} else {use=3; mad=0;box("You have the first chance to play!");} delay(2000); do { for(int j=0;j<8;j++) {dang[j]=0;my[j]=0;} count++; mad++;bre=0; if((end!=1)&&(mad!=1)) { switch(use) { case 0:{ switch(count) { case 1: col[2][2]=comps;break; case 2: {if(col[1][1]==hums) {col[0][0]=comps;play[0]=1;} else if((col[2][0]==hums)||(col[2][1]==hums)) {col[0][2]=comps;play[1]=1;} else if((col[0][1]==hums)) {col[0][2]=comps;play[3]=1;} else if((col[1][0]==hums)) {col[2][0]=comps;play[4]=1;} else if((col[0][2]==hums)||(col[1][2]==hums)) {col[2][0]=comps;play[2]=1;} else if (col[0][0]==hums) {col[0][2]=comps;play[3]=1;} else dont=1; }break; case 3:{if(play[0]==1) dont=1; else if((play[1]==1)&&(col[1][2]==hums)) {col[0][0]=comps;} else if((play[2]==1)&&(col[2][1]==hums)) {col[0][0]=comps;} else if((play[3]==1)&&((col[2][1]==hums)||(col[1][2]==hums))) {col[2][0]=comps;} else if((play[4]==1)&&(col[2][1]==hums)) {col[0][2]=comps;} else dont=1; }break; case 4:dont=1;break; } }break; case 1:{switch(count) { case 1:col[0][1]=comps;break; case 2:{if(col[2][0]==hums) col[0][0]=comps; else if(col[1][0]==hums) col[0][0]=comps; else if(col[0][2]==hums) col[1][0]=comps; else if(col[1][2]==hums) col[0][2]=comps; else if(col[0][0]==hums) col[1][2]=comps; else if(col[2][2]==hums) col[0][2]=comps; else if(q<=1) col[2][2]=comps; else col[2][0]=comps; } break; case 3:dont=1; } }break; case 2:{switch(count) { case 1:col[1][1]=comps;break; case 2:dont=1; } }break; case 3:{dont=1; }break; } if(dont==1) { for(int i=0,l=2;i<3;i++,l--) { if(col[i][i]==hums) dang[0]++; else if(col[i][i]==comps) my[0]++; if(col[i][l]==hums) dang[1]++; else if(col[i][l]==comps) my[1]++; } for(j=0;j<3;j++) { for(int k=0;k<3;k++) { if(col[j][k]==hums) dang[j+2]++; else if(col[j][k]==comps) my[j+2]++; if(col[k][j]==hums) dang[j+5]++; else if(col[k][j]==comps) my[j+5]++; } } for(int j=0;j<8;j++) { if((my[j]==3)||(dang[j]==3)||(count==5)) end=1; if((dang[j]==2)&&(my[j]!=0)) dang[j]=0; if((my[j]==2)&&(dang[j]==0)) {my[j]=3;bre=1;} } if(bre==1) {for(j=0;j<8;j++) dang[j]=0; } if((dang[0]==2)||(my[0]==3)) { for(int i=0;i<3;i++) { if(col[i][i]==' ') col[i][i]=comps; }} else if((dang[1]==2)||(my[1]==3)) { for(int i=0,l=2;i<3;i++,l--) { if(col[i][l]==' ') col[i][l]=comps; }} else if((dang[2]==2)||(my[2]==3)||(dang[3]==2)||(my[3]==3)||(dang[4]==2)||(my[4 ]==3)) { for(j=0;j<3;j++) {if((dang[j+2]==2)||(my[j+2]==3)) for(int k=0;k<3;k++) {if(col[j][k]==' ') {col[j][k]=comps;bre=1;}} } } else if((dang[5]==2)||(my[5]==3)||(dang[6]==2)||(my[6]==3)||(dang[7]==2)||(my[7 ]==3)) { for(int j=0;j<3;j++) {if((dang[j+5]==2)||(my[j+5]==3)) for(int k=0;k<3;k++) {if(col[k][j]==' ') {col[k][j]=comps;bre=1;}} } } else if(col[1][1]==' ') col[1][1]=comps; else if((use==2)&&(col[2][2]==' ')) col[2][2]=comps; else if((use==2)&&(col[0][2]==' ')) col[0][2]=comps; else if((((col[0][0]==hums)&&(col[2][2]==hums))||((col[0][2]==hums)&&(col[2][0] ==hums)))&&(col[1][2]==' ')) col[1][2]=comps; else if((col[1][1]!=hums)&&((col[0][0]==hums)||(col[2][2]==hums))&&((col[0][1]= =hums)||(col[1][2]==hums))&&(col[0][2]==' ')) col[0][2]=comps; else if((col[1][1]!=hums)&&((col[0][0]==hums)||(col[2][2]==hums))&&((col[1][0]= =hums)||(col[2][1]==hums))&&(col[2][0]==' ')) col[2][0]=comps; else if((col[1][1]!=hums)&&((col[0][2]==hums)||(col[2][0]==hums))&&((col[2][1]= =hums)||(col[1][2]==hums))&&(col[2][2]==' ')) col[2][2]=comps; else if((col[1][1]!=hums)&&((col[0][2]==hums)||(col[2][0]==hums))&&((col[0][1]= =hums)||(col[1][0]==hums))&&(col[0][0]==' ')) col[0][0]=comps; else if((col[1][1]!=comps)&&(col[2][2]==' ')) col[2][2]=comps; else if((col[1][1]!=comps)&&(col[0][2]==' ')) col[0][2]=comps; else if(col[0][0]==' ') col[0][0]=comps; else if(col[2][2]==' ') col[2][2]=comps; else if(col[0][1]==' ') col[0][1]=comps; else if(col[1][2]==' ') col[1][2]=comps; else if(col[0][2]==' ') col[0][2]=comps; else if(col[2][0]==' ') col[2][0]=comps; else if(col[1][0]==' ') col[1][0]=comps; else if(col[2][1]==' ') col[2][1]=comps; } for(int i=0;i<8;i++) {if(my[i]==3) end=1; } } star: draw(col); box(" "); if(end!=1) { box("play"); madu=getche(); if((int(madu)<49)||(int(madu)>57)) {box("INVALID ENTRY!");for(long double jk=0;jk<99999999;jk++);goto star;} inpu=int(madu)-48; p=(inpu-1)/3; switch(inpu%3) {case 0:q=2;break; case 1:q=0;break; case 2:q=1;break; } if(col[p][q]!=' ') {box("Space is already occupied!");for(long double jk=0;jk<99999999;jk++);goto star;} col[p][q]=hums; } for(j=0;j<8;j++) {dang[j]=0;my[j]=0;} for(int i=0,l=2;i<3;i++,l--) { if(col[i][i]==hums) dang[0]++; else if(col[i][i]==comps) my[0]++; if(col[i][l]==hums) dang[1]++; else if(col[i][l]==comps) my[1]++; } for(j=0;j<3;j++) { for(int k=0;k<3;k++) { if(col[j][k]==hums) dang[j+2]++; else if(col[j][k]==comps) my[j+2]++; if(col[k][j]==hums) dang[j+5]++; else if(col[k][j]==comps) my[j+5]++; } } for(j=0;j<8;j++) {if((my[j]==3)||(dang[j]==3)) end=1; } }while((end!=1)); draw(col); for(int asd=0;asd<6;asd++) {many=many+1; if((my[0]==3)||(dang[0]==3)) {exii=0; if(many%2==1) for(int m=0,n=0;m<3;m++,n++) { setfillstyle(1,BLUE);floodfill(193+m*85,118+n*85,15); } else for(int m=0,n=0;m<3;m++,n++) { setfillstyle(1,BLACK);floodfill(193+m*85,118+n*85,15); }} else if((my[1]==3)||(dang[1]==3)) {exii=0; if(many%2==1) for(int m=0,n=2;m<3;m++,n--) { setfillstyle(1,BLUE);floodfill(193+m*85,118+n*85,15); } else for(int m=0,n=2;m<3;m++,n--) { setfillstyle(1,BLACK);floodfill(193+m*85,118+n*85,15); }} else for(j=2;j<8;j++) {if(((my[j]==3)||(dang[j]==3))&&(j<5)) {exii=0; if(many%2==1) for(int m=0,n=j-2;m<3;m++) { setfillstyle(1,BLUE);floodfill(193+m*85,118+n*85,15); } else for(int m=0,n=j-2;m<3;m++) { setfillstyle(1,BLACK);floodfill(193+m*85,118+n*85,15); }} else if((my[j]==3)||(dang[j]==3)) {exii=0; if(many%2==1) for(int m=0,n=j-5;m<3;m++) { setfillstyle(1,BLUE);floodfill(193+n*85,118+m*85,15); } else for(int m=0,n=j-5;m<3;m++) { setfillstyle(1,BLACK);floodfill(193+n*85,118+m*85,15); }} } for(long double jk=0;jk<9999999;jk++); if(exii==1)break; } for(int m=0;m<8;m++) { if(my[m]==3) result=1; } for(m=0;m<8;m++) { if(dang[m]==3) result=2; } switch(result) {case 1:box("You loose! Want to try again(y/n)");break; case 2:box("You win! Want to try again(y/n)");break; default:box("The game is draw! Want to try again(y/n)");break; } input=getche(); }while(input=='Y'||input=='y'); clearviewport(); for(long double mas=0;mas<=99999999;mas++); exit(0); }
clrscr() Function in C++
It is a predefined function in "conio.h" (console input output header file) used to clear the console screen. It is a predefined function, by using this function we can clear the data from console (Monitor). Using of clrscr() is always optional but it should be place after variable or function declaration only. It is often used at the beginning of the program (mostly after variable declaration but not necessarily) so that the console is clear for our output.
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/* clrscr() function is also a non-standard function defined in "conio.h" header. This function is used to clear the console screen. It is often used at the beginning of the program (mostly after variable declaration but not necessarily) so that the console is clear for our output.*/ #include<iostream.h> #include<conio.h> void main() { int a=10, b=20; int sum=0; clrscr(); // use clrscr() after variable declaration sum=a+b; cout<<"Sum: "<<sum; //clear the console screen clrscr(); getch(); }
getimage() Function in C++
getimage() function copy a specific portion into memory. This specific image would be any bit image like rectangle, circle or anything else. getimage() copies an image from the screen to memory. Left, top, right, and bottom define the screen area to which the rectangle is copied. Bitmap points to the area in memory where the bit image is stored. The first two words of this area are used for the width and height of the rectangle; the remainder holds the image itself.
Syntax for getimage() Function in C++
#include <graphics.h> void getimage(int left, int top, int right, int bottom, void *bitmap);
left
X coordinate of top left corner
top
Y coordinate of top left corner
right
X coordinate of bottom right corner
bottom
Y coordinate of bottom right corner
bitmap
points to the area in memory where the bit image is stored getimage() function saves a bit image of specified region into memory, region can be any rectangle. This function does not return any value.
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/* getimage() function code example copies an image from the screen to memory. */ /* save a bit image of the specified region displayed on the screen into memory by getimage() function code example. */ #include<stdio.h> #include<conio.h> #include<graphics.h> void main() { int gd=DETECT, gm,size; char *buff; initgraph(&gd,&gm," "); outtextxy(100,80,"Original image:"); rectangle(100,200,200,275); size=http://www.web.com/imagesize(100,200,200,275); buf=malloc(size); getimage(100,200,200,275,buf); outtextxy(100,320,"Captured image:"); putimage(100,340,buf,COPY_PUT); getch(); closegraph(); }
setfillstyle() Function in C++
The header file graphics.h contains setfillstyle() function which sets the current fill pattern and fill color. Current fill pattern and fill color is used to fill the area. setfillstyle sets the current fill pattern and fill color. To set a user-defined fill pattern, do not give a pattern of 12 (USER_FILL) to setfillstyle; instead, call setfillpattern.
Syntax for setfillstyle() Function in C++
#include<graphics.h> void setfillstyle(int pattern, int color);
color
Specify the color • BLACK – 0 • BLUE – 1 • GREEN – 2 • CYAN – 3 • RED – 4 • MAGENTA – 5 • BROWN – 6 • LIGHTGRAY – 7 • DARKGRAY – 8 • LIGHTBLUE – 9 • LIGHTGREEN – 10 • LIGHTCYAN – 11 • LIGHTRED – 12 • LIGHTMAGENTA – 13 • YELLOW – 14 • WHITE – 15
pattern
Specify the pattern • EMPTY_FILL – 0 • SOLID_FILL – 1 • LINE_FILL – 2 • LTSLASH_FILL – 3 • SLASH_FILL – 4 • BKSLASH_FILL – 5 • LTBKSLASH_FILL – 6 • HATCH_FILL – 7 • XHATCH_FILL – 8 • INTERLEAVE_FILL – 9 • WIDE_DOT_FILL – 10 • CLOSE_DOT_FILL – 11 • USER_FILL – 12 If invalid input is passed to setfillstyle, graphresult returns -1(grError), and the current fill pattern and fill color remain unchanged. The EMPTY_FILL style is like a solid fill using the current background color (which is set by setbkcolor). This function does not return any value.
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/* The header file graphics.h contains setfillstyle() function which sets the current fill pattern and fill color. floodfill() function is used to fill an enclosed area. Current fill pattern and fill color is used to fill the area. */ #include <graphics.h> // driver code int main() { // gm is Graphics mode which is // a computer display mode that // generates image using pixels. // DETECT is a macro defined in // "graphics.h" header file int gd = DETECT, gm; // initgraph initializes the // graphics system by loading // a graphics driver from disk initgraph(&gd, &gm, " "); // center and radius of circle int x_circle = 250; int y_circle = 250; int radius=100; // setting border color int border_color = WHITE; // set color and pattern setfillstyle(HATCH_FILL,RED); // x and y is a position and // radius is for radius of circle circle(x_circle,y_circle,radius); // fill the color at location // (x, y) with in border color floodfill(x_circle,y_circle,border_color); getch(); // closegraph function closes the // graphics mode and deallocates // all memory allocated by // graphics system closegraph(); return 0; }
Break Statement in C++
Break statement in C++ is a loop control statement defined using the break keyword. It is used to stop the current execution and proceed with the next one. When a compiler calls the break statement, it immediately stops the execution of the loop and transfers the control outside the loop and executes the other statements. In the case of a nested loop, break the statement stops the execution of the inner loop and proceeds with the outer loop. The statement itself says it breaks the loop. When the break statement is called in the program, it immediately terminates the loop and transfers the flow control to the statement mentioned outside the loop.
Syntax for Break Statement in C++
// jump-statement; break;
The break statement is used in the following scenario: • When a user is not sure about the number of iterations in the program. • When a user wants to stop the program based on some condition. The break statement terminates the loop where it is defined and execute the other. If the condition is mentioned in the program, based on the condition, it executes the loop. If the condition is true, it executes the conditional statement, and if the break statement is mentioned, it will immediately break the program. otherwise, the loop will iterate until the given condition fails. if the condition is false, it stops the program.
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/* break statement with while loop code example */ // program to find the sum of positive numbers // if the user enters a negative numbers, break ends the loop // the negative number entered is not added to sum #include <iostream> using namespace std; int main() { int number; int sum = 0; while (true) { // take input from the user cout << "Enter a number: "; cin >> number; // break condition if (number < 0) { break; } // add all positive numbers sum += number; } // display the sum cout << "The sum is " << sum << endl; return 0; }
If Else Statement in C++
In computer programming, we use the if statement to run a block code only when a certain condition is met. An if statement can be followed by an optional else statement, which executes when the boolean expression is false. There are three forms of if...else statements in C++: • if statement, • if...else statement, • if...else if...else statement,
Syntax for If Statement in C++
if (condition) { // body of if statement }
The if statement evaluates the condition inside the parentheses ( ). If the condition evaluates to true, the code inside the body of if is executed. If the condition evaluates to false, the code inside the body of if is skipped.
Syntax for If...Else Statement
if (condition) { // block of code if condition is true } else { // block of code if condition is false }
The if..else statement evaluates the condition inside the parenthesis. If the condition evaluates true, the code inside the body of if is executed, the code inside the body of else is skipped from execution. If the condition evaluates false, the code inside the body of else is executed, the code inside the body of if is skipped from execution. The if...else statement is used to execute a block of code among two alternatives. However, if we need to make a choice between more than two alternatives, we use the if...else if...else statement.
Syntax for If...Else...Else If Statement in C++
if (condition1) { // code block 1 } else if (condition2){ // code block 2 } else { // code block 3 }
• If condition1 evaluates to true, the code block 1 is executed. • If condition1 evaluates to false, then condition2 is evaluated. • If condition2 is true, the code block 2 is executed. • If condition2 is false, the code block 3 is executed. There can be more than one else if statement but only one if and else statements. In C/C++ if-else-if ladder helps user decide from among multiple options. The C/C++ if statements are executed from the top down. As soon as one of the conditions controlling the if is true, the statement associated with that if is executed, and the rest of the C else-if ladder is bypassed. If none of the conditions is true, then the final else statement will be executed.
Syntax for If Else If Ladder in C++
if (condition) statement 1; else if (condition) statement 2; . . else statement;
Working of the if-else-if ladder: 1. Control falls into the if block. 2. The flow jumps to Condition 1. 3. Condition is tested. If Condition yields true, goto Step 4. If Condition yields false, goto Step 5. 4. The present block is executed. Goto Step 7. 5. The flow jumps to Condition 2. If Condition yields true, goto step 4. If Condition yields false, goto Step 6. 6. The flow jumps to Condition 3. If Condition yields true, goto step 4. If Condition yields false, execute else block. Goto Step 7. 7. Exits the if-else-if ladder. • The if else ladder statement in C++ programming language is used to check set of conditions in sequence. • This is useful when we want to selectively executes one code block(out of many) based on certain conditions. • It allows us to check for multiple condition expressions and execute different code blocks for more than two conditions. • A condition expression is tested only when all previous if conditions in if-else ladder is false. • If any of the conditional expression evaluates to true, then it will execute the corresponding code block and exits whole if-else ladder.
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/* If Else Statement in C++ Language */ #include <iostream> using namespace std; int main () { // local variable declaration: int a = 100; // check the boolean condition if( a < 20 ) { // if condition is true then print the following cout << "a is less than 20;" << endl; } else { // if condition is false then print the following cout << "a is not less than 20;" << endl; } cout << "value of a is : " << a << endl; return 0; }
getche() Function in C++
This function waits for any character input from keyboard. And, it will also echo the input character on to the output screen. The getch() function is very useful if you want to read a character input from the keyboard. Like getch(), getche() is also character input functions. It is unformatted input function meaning it does not allow user to read input in their format. Difference between getch() and getche() is that getche() echoes pressed character. getche() also returns character pressed like getch(). It is also defined in header file conio.h.
Syntax for getche() Function in C++
int getche( void );
This function return the character read from the keyboard. getche() reads a single character from the keyboard and echoes it to the current text window, using direct video or BIOS.
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/* getche() function is a function in C programming language which waits for any character input from keyboard and it will also echo the input character on to the output screen. Please find below the description and syntax for above file handling function. */ int chcount = 0, wdcount =0, count = 0; char ch=' '; cout << "Enter your text : "; while ( ch != '\r' ) { if ( ch !=' ' ) { chcount++; count++; } else if (count > 2) { wdcount++; count=0; } ch = getche(); } if (count >2) //validate that last word is counted wdcount++; cout<<"\nCount of words is: "<<wdcount<<"\nCount of charcters is: "<<chcount<<"\n"; system("pause"); return 0;
imagesize() Function in C++
The header file graphics.h contains imagesize() function which returns the number of bytes required to store a bit-image. This function is used when we are using getimage. imagesize() function returns the required memory area to store an image in bytes. imagesize() function returns the number of bytes needed to store the top-left corner of the screen at left, top and the bottom-right corner at right, bottom. This function is usually used in conjunction with the getimage() function. The imagesize() function only works in graphics mode.
Syntax for imagesize() Function in C++
unsigned int imagesize(int left, int top, int right, int bottom);
left
X coordinate of top left corner
top
Y coordinate of top left corner
right
X coordinate of bottom right corner
bottom
Y coordinate of bottom right corner left, top, right, and bottom define the area of the screen in which image is stored.
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/* imagesize() function returns the number of bytes required to store a bitimage. */ /* get the number of bytes required to store a bit-image by imagesize() function code example. */ #include <graphics.h> #include <stdio.h> // driver code int main() { // gm is Graphics mode which is // a computer display mode that // generates image using pixels. // DETECT is a macro defined in // "graphics.h" header file int gd = DETECT, gm, color, bytes; char arr[100]; // initgraph initializes the // graphics system by loading a // graphics driver from disk initgraph(&gd, &gm, ""); // Draws a circle with center at // (200, 200) and radius as 50. circle(200, 200, 50); // draws a line with 2 points line(150, 200, 250, 200); // draws a line with 2 points line(200, 150, 200, 250); // imagesize function bytes = imagesize(150, 150, 250, 250); // sprintf stands for "String print". // Instead of printing on console, // it store output on char buffer // which are specified in sprintf sprintf(arr, "Number of bytes required " "to store required area = %d", bytes); // outtext function displays text // at current position. outtextxy(20, 280, arr); getch(); // closegraph function closes the // graphics mode and deallocates // all memory allocated by // graphics system . closegraph(); return 0; }
Standard Library malloc() Function in C++
Allocate memory block. Allocates a block of size bytes of memory, returning a pointer to the beginning of the block. The content of the newly allocated block of memory is not initialized, remaining with indeterminate values. If size is zero, the return value depends on the particular library implementation (it may or may not be a null pointer), but the returned pointer shall not be dereferenced. Malloc function in C++ is used to allocate a specified size of the block of memory dynamically uninitialized. It allocates the memory to the variable on the heap and returns the void pointer pointing to the beginning address of the memory block. The values in the memory block allocated remain uninitialized and indeterminate. In case the size specified in the function is zero then pointer returned must not be dereferenced as it can be a null pointer, and in this case, behavior depends on particular library implementation. When a memory block is allocated dynamically memory is allocated on the heap but the pointer is allocated to the stack.
Syntax for malloc() Function in C++
#include <cstdlib> void* malloc (size_t size);
size
Size of the memory block, in bytes. size_t is an unsigned integral type. On success, a pointer to the memory block allocated by the function. The type of this pointer is always void*, which can be cast to the desired type of data pointer in order to be dereferenceable. If the function failed to allocate the requested block of memory, a null pointer is returned.
Advantages of malloc() in C++
There are a lot of advantages to using the malloc method in one's application: • Dynamic Memory allocation: Usually we create arrays at compile time in C++, the size of such arrays is fixed. In the case at run time we do not use all the space or extra space is required for more elements to be inserted in the array, then this leads to improper memory management or segmentation fault error. • Heap memory: Local arrays that are defined at compile time are allocated on the stack, which has lagged in memory management in case the number of data increases. Thus one needs to allocate memory out of the stack, thus malloc comes into the picture as it allocates the memory location on the heap and returns a pointer on the stack pointing to the starting address of the array type memory being allocated. • Variable-length array: This function helps to allocate memory for an array whose size can be defined at the runtime. Thus one can create the number of blocks as much as required at run time. • Better lifetime: Variable created using malloc method is proved to have a better life than the local arrays as a lifetime of local arrays depends on the scope they are being defined and cannot access out of their scope. But variables or arrays created using malloc exist till they are freed. This is of great importance for various data structures such as linked list, binary heap, etc.
Differences between the malloc() and new
• The new operator constructs an object, i.e., it calls the constructor to initialize an object while malloc() function does not call the constructor. The new operator invokes the constructor, and the delete operator invokes the destructor to destroy the object. This is the biggest difference between the malloc() and new. • The new is an operator, while malloc() is a predefined function in the stdlib header file. • The operator new can be overloaded while the malloc() function cannot be overloaded. • If the sufficient memory is not available in a heap, then the new operator will throw an exception while the malloc() function returns a NULL pointer. • In the new operator, we need to specify the number of objects to be allocated while in malloc() function, we need to specify the number of bytes to be allocated. • In the case of a new operator, we have to use the delete operator to deallocate the memory. But in the case of malloc() function, we have to use the free() function to deallocate the memory.
Data races
Only the storage referenced by the returned pointer is modified. No other storage locations are accessed by the call. If the function reuses the same unit of storage released by a deallocation function (such as free or realloc), the functions are synchronized in such a way that the deallocation happens entirely before the next allocation.
Exceptions
No-throw guarantee: this function never throws exceptions.
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/* allocate the requested size of bytes and it returns a pointer to the first byte of allocated memory by malloc() function code example. */ #include <iostream> #include <cstdlib> using namespace std; int main() { // allocate 5 int memory blocks int* ptr = (int*) malloc(5 * sizeof(int)); // check if memory has been allocated successfully if (!ptr) { cout << "Memory Allocation Failed"; exit(1); } cout << "Initializing values..." << endl << endl; for (int i = 0; i < 5; i++) { ptr[i] = i * 2 + 1; } cout << "Initialized values" << endl; // print the values in allocated memories for (int i = 0; i < 5; i++) { // ptr[i] and *(ptr+i) can be used interchangeably cout << *(ptr + i) << endl; } // deallocate memory free(ptr); return 0; }
outtextxy() Function in C++
outtextxy displays a text string in the viewport at the given position (x, y), using the current justification settings and the current font, direction, and size. To maintain code compatibility when using several fonts, use textwidth and textheight to determine the dimensions of the string. If a string is printed with the default font using outtext or outtextxy, any part of the string that extends outside the current viewport is truncated. outtextxy is for use in graphics mode; it will not work in text mode.
Syntax for outtextxy() Function in C++
#include <graphics.h> void outtextxy(int x, int y, char *string);
x
x-coordinate of the point
y
y-coordinate of the point
string
string to be displayed where, x, y are coordinates of the point and, third argument contains the address of string to be displayed. This function does not return any value.
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/* outtextxy() function displays the text or string at a specified point (x, y) on the screen. */ // C++ Implementation for outtextxy() #include <graphics.h> int main() { textcolor(RED); cleardevice(); setcolor(RED); outtextxy(150,205,"Enter the Username:"); outtextxy(150,245,"Enter the Password:"); outtextxy(150,355,"Thank you"); outtextxy(150,445,"nice job"); outtextxy(50,105,"good day"); outtextxy(50,145,"pan"); outtextxy(50,255,"go"); outtextxy(50,245,"nice day"); return 0; }
initgraph() Function in C++
To create a program in Graphics Mode, the first step would be to include the header file graphics.h. This file is required for Graphics programming. After this, the graphics have to be initialized. C Language supports 16 Bit's MS-DOS environment. Initializing the Graphics mode is to call various functions, one such is called initgraph. initgraph initializes the graphics system by loading a graphics driver from disk (or validating a registered driver), and putting the system into graphics mode. To start the graphics system, first call the initgraph function. initgraph loads the graphics driver and puts the system into graphics mode. You can tell initgraph to use a particular graphics driver and mode, or to autodetect the attached video adapter at run time and pick the corresponding driver. If you tell initgraph to autodetect, it calls detectgraph to select a graphics driver and mode. initgraph also resets all graphics settings to their defaults (current position, palette, color, viewport, and so on) and resets graphresult to 0.
Syntax for initgraph() Function in C++
void initgraph (int *graphdriver, int *graphmode, char *pathtodriver);
graphdriver
This is an integer that indicates that the graphics driver has been used.
graphmode
It is also an integer value that detects the available graphics driver and initializes the graphics mode according to its highest resolution.
pathtodriver
This is the path of the directory that first searches the initgraph function graphics driver. If the graphics driver is not available then the system searches it in the current directory. It is necessary to pass the correct value of the three parameters in the initgraph function or else an unpredictable output is obtained.
intgd = DETECT, gm; initgraph (&gd, &gm, " ");
To initialize Graphics mode, you only have to write two lines. Here, we have taken two integer variables 'd' and 'm'. Here, DETECT is an enumeration type that identifies and identifies the proper graphics driver. The initgraph function has to pass the address of both the variables. You can see in the example that we have given a space at the position of the third variable. This means that if you do not know the driver's path then you can leave it blank. The compiler will auto-detect the path. initgraph always sets the internal error code; on success, it sets the code to 0. If an error occurred, *graphdriver is set to -2, -3, -4, or -5, and graphresult returns the same value as listed below: • grNotDetected -2 Cannot detect a graphics card • grFileNotFound -3 Cannot find driver file • grInvalidDriver -4 Invalid driver • grNoLoadMem -5 Insufficient memory to load driver
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/* initgraph initializes the graphics system by loading a graphics driver from disk (or validating a registered driver), and putting the system into graphics mode. To start the graphics system, first call the initgraph function. initgraph loads the graphics driver and puts the system into graphics mode. You can tell initgraph to use a particular graphics driver and mode, or to autodetect the attached video adapter at run time and pick the corresponding driver. */ int DGraphics::Init( int gmode ) { int gdriver = VGA, errorcode; gdriver=installuserdriver("SVGA256",NULL); initgraph(&gdriver, &gmode, ""); if ( (errorcode = graphresult()) != grOk ) { cout << "Error: Graphics - %s\n" << grapherrormsg(errorcode); return FALSE; } ActiveMode=gmode; return TRUE; }
delay() Function in C++
delay() function is used to hold the program's execution for given number of milliseconds, it is declared in dos.h header file. There can be many instances when we need to create a delay in our programs. C++ provides us with an easy way to do so. We can use a delay() function for this purpose in our code. We can run the code after a specific time in C++ using delay() function.
Syntax for delay() Function in C++
void delay(unsigned int milliseconds);
milliseconds
how many milliseconds to delay The function takes one parameter which is unsigned integer. Here, void suggests that this function returns nothing. 'delay' is the function name.
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/* hold the program's execution for given number of milliseconds by delay() function code example. */ #include<iostream.h> #include<dos.h> //for delay() #include<conio.h> //for getch() int main() { clrscr(); int n; cout<<"Enter the delay (in seconds) you want to make after giving input."<<endl; cin>>n; delay(n*1000); cout<<"This has been printed after "<< n <<" seconds delay"; getch(); return 0; }
putimage() Function in C++
putimage puts the bit image previously saved with getimage back onto the screen, with the upper left corner of the image placed at (left,top). bitmap points to the area in memory where the source image is stored. The op parameter to putimage specifies a combination operator that controls how the color for each destination pixel onscreen is computed, based on the pixel already onscreen and the corresponding source pixel in memory.
Syntax for putimage() Function in C++
#include <graphics.h> void putimage(int left, int top, void *bitmap, int op);
left
X coordinate of top left corner of the specified rectangular area
top
Y coordinate of top left corner of the specified rectangular area
bitmap
pointer to the bitmap image in memory
op
operator for putimage. The enumeration putimage_ops, as defined in graphics.h, gives names to these operators. • COPY_PUT 0 Copy • XOR_PUT 1 Exclusive or • OR_PUT 2 Inclusive or • AND_PUT 3 And • NOT_PUT 4 Copy the inverse of the source In other words, COPY_PUT copies the source bitmap image onto the screen, XOR_PUT XORs the source image with the image already onscreen, OR_PUT ORs the source image with that onscreen, and so on. This function does not return any value.
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/* In C++, the putimage() function is used to put the bit image that is saved with getimage() function back to screen. */ /* put the bit image to screen by putimage() function code example */ #include<graphics.h> #include<conio.h> #include<stdlib.h> main() { int gd = DETECT, gm, area, temp1, temp2, left = 25, top = 75; void *p; initgraph(&gd,&gm,"C:\\TC\\BGI"); setcolor(YELLOW); circle(50,100,25); setfillstyle(SOLID_FILL,YELLOW); floodfill(50,100,YELLOW); setcolor(BLACK); setfillstyle(SOLID_FILL,BLACK); fillellipse(44,85,2,6); fillellipse(56,85,2,6); ellipse(50,100,205,335,20,9); ellipse(50,100,205,335,20,10); ellipse(50,100,205,335,20,11); area = imagesize(left, top, left + 50, top + 50); p = malloc(area); setcolor(WHITE); settextstyle(SANS_SERIF_FONT,HORIZ_DIR,2); outtextxy(155,451,"Smiling Face Animation"); setcolor(BLUE); rectangle(0,0,639,449); while(!kbhit()) { temp1 = 1 + random ( 588 ); temp2 = 1 + random ( 380 ); getimage(left, top, left + 50, top + 50, p); putimage(left, top, p, XOR_PUT); putimage(temp1 , temp2, p, XOR_PUT); delay(100); left = temp1; top = temp2; } getch(); closegraph(); return 0; }
Switch Case Statement in C++
Switch statement in C tests the value of a variable and compares it with multiple cases. Once the case match is found, a block of statements associated with that particular case is executed. Each case in a block of a switch has a different name/number which is referred to as an identifier. The value provided by the user is compared with all the cases inside the switch block until the match is found. If a case match is NOT found, then the default statement is executed, and the control goes out of the switch block.
Syntax for Switch Case Statement in C++
switch( expression ) { case value-1: Block-1; Break; case value-2: Block-2; Break; case value-n: Block-n; Break; default: Block-1; Break; } Statement-x;
• The expression can be integer expression or a character expression. • Value-1, 2, n are case labels which are used to identify each case individually. Remember that case labels should not be same as it may create a problem while executing a program. Suppose we have two cases with the same label as '1'. Then while executing the program, the case that appears first will be executed even though you want the program to execute a second case. This creates problems in the program and does not provide the desired output. • Case labels always end with a colon ( : ). Each of these cases is associated with a block. • A block is nothing but multiple statements which are grouped for a particular case. • Whenever the switch is executed, the value of test-expression is compared with all the cases which we have defined inside the switch. Suppose the test expression contains value 4. This value is compared with all the cases until case whose label four is found in the program. As soon as a case is found the block of statements associated with that particular case is executed and control goes out of the switch. • The break keyword in each case indicates the end of a particular case. If we do not put the break in each case then even though the specific case is executed, the switch in C will continue to execute all the cases until the end is reached. This should not happen; hence we always have to put break keyword in each case. Break will terminate the case once it is executed and the control will fall out of the switch. • The default case is an optional one. Whenever the value of test-expression is not matched with any of the cases inside the switch, then the default will be executed. Otherwise, it is not necessary to write default in the switch. • Once the switch is executed the control will go to the statement-x, and the execution of a program will continue.
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/* the switch statement helps in testing the equality of a variable against a set of values */ #include <iostream> using namespace std; int main () { // local variable declaration: char grade = 'D'; switch(grade) { case 'A' : cout << "Excellent!" << endl; break; case 'B' : case 'C' : cout << "Well done" << endl; break; case 'D' : cout << "You passed" << endl; break; case 'F' : cout << "Better try again" << endl; break; default : cout << "Invalid grade" << endl; } cout << "Your grade is " << grade << endl; return 0; }
For Loop Statement in C++
In computer programming, loops are used to repeat a block of code. For example, when you are displaying number from 1 to 100 you may want set the value of a variable to 1 and display it 100 times, increasing its value by 1 on each loop iteration. When you know exactly how many times you want to loop through a block of code, use the for loop instead of a while loop. A for loop is a repetition control structure that allows you to efficiently write a loop that needs to execute a specific number of times.
Syntax of For Loop Statement in C++
for (initialization; condition; update) { // body of-loop }
initialization
initializes variables and is executed only once.
condition
if true, the body of for loop is executed, if false, the for loop is terminated.
update
updates the value of initialized variables and again checks the condition. A new range-based for loop was introduced to work with collections such as arrays and vectors.
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/* For Loop Statement in C++ Language */ // C++ program to find the sum of first n natural numbers // positive integers such as 1,2,3,...n are known as natural numbers #include <iostream> using namespace std; int main() { int num, sum; sum = 0; cout << "Enter a positive integer: "; cin >> num; for (int i = 1; i <= num; ++i) { sum += i; } cout << "Sum = " << sum << endl; return 0; }
getch() Function in C++
The getch() is a predefined non-standard function that is defined in conio.h header file. It is mostly used by the Dev C/C++, MS- DOS's compilers like Turbo C to hold the screen until the user passes a single value to exit from the console screen. It can also be used to read a single byte character or string from the keyboard and then print. It does not hold any parameters. It has no buffer area to store the input character in a program.
Syntax for getch() Function in C++
#include <conio.h> int getch(void);
The getch() function does not accept any parameter from the user. It returns the ASCII value of the key pressed by the user as an input. We use a getch() function in a C/ C++ program to hold the output screen for some time until the user passes a key from the keyboard to exit the console screen. Using getch() function, we can hide the input character provided by the users in the ATM PIN, password, etc. • getch() method pauses the Output Console until a key is pressed. • It does not use any buffer to store the input character. • The entered character is immediately returned without waiting for the enter key. • The entered character does not show up on the console. • The getch() method can be used to accept hidden inputs like password, ATM pin numbers, etc.
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/* wait for any character input from keyboard by getch() function code example. The getch() function is very useful if you want to read a character input from the keyboard. */ // C code to illustrate working of // getch() to accept hidden inputs #include<iostream.h> #include<conio.h> void main() { int a=10, b=20; int sum=0; clrscr(); sum=a+b; cout<<"Sum: "<<sum; getch(); // use getch() befor end of main() }
settextstyle() Function in C++
Settextstyle function is used to change the way in which text appears, using it we can modify the size of text, change direction of text and change the font of text. settextstyle sets the text font, the direction in which text is displayed, and the size of the characters. A call to settextstyle affects all text output by outtext and outtextxy.
Syntax for settextstyle() Function in C++
#include <graphics.h> void settextstyle(int font, int direction, int charsize);
font
One 8x8 bit-mapped font and several "stroked" fonts are available. The 8x8 bit-mapped font is the default. The enumeration font_names, which is defined in graphics.h, provides names for these different font settings: • DEFAULT_FONT – 0 8x8 bit-mapped font • TRIPLEX_FONT – 1 Stroked triplex font • SMALL_FONT – 2 Stroked small font • SANS_SERIF_FONT – 3 Stroked sans-serif font • GOTHIC_FONT – 4 Stroked gothic font • SCRIPT_FONT – 5 Stroked script font • SIMPLEX_FONT – 6 Stroked triplex script font • TRIPLEX_SCR_FONT – 7 Stroked triplex script font • COMPLEX_FONT – 8 Stroked complex font • EUROPEAN_FONT – 9 Stroked European font • BOLD_FONT – 10 Stroked bold font The default bit-mapped font is built into the graphics system. Stroked fonts are stored in *.CHR disk files, and only one at a time is kept in memory. Therefore, when you select a stroked font (different from the last selected stroked font), the corresponding *.CHR file must be loaded from disk. To avoid this loading when several stroked fonts are used, you can link font files into your program. Do this by converting them into object files with the BGIOBJ utility, then registering them through registerbgifont.
direction
Font directions supported are horizontal text (left to right) and vertical text (rotated 90 degrees counterclockwise). The default direction is HORIZ_DIR. The size of each character can be magnified using the charsize factor. If charsize is nonzero, it can affect bit-mapped or stroked characters. A charsize value of 0 can be used only with stroked fonts.
charsize
• If charsize equals 1, outtext and outtextxy displays characters from the 8x8 bit-mapped font in an 8x8 pixel rectangle onscreen. • If charsize equals 2, these output functions display characters from the 8x8 bit-mapped font in a 16*16 pixel rectangle, and so on (up to a limit of ten times the normal size). • When charsize equals 0, the output functions outtext and outtextxy magnify the stroked font text using either the default character magnification factor (4) or the user-defined character size given by setusercharsize. Always use textheight and textwidth to determine the actual dimensions of the text. This function needs to be called before the outtextxy() function, otherwise there will be no effect on text and output will be the same.
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/* settextstyle() function sets the current text font, direction and character size. All calls to outtext() and outtextxy() are affected by the new settings. */ int main() { int gm, gd; gd = VGA; gm = VGAHI; initgraph(&gd, &gm, ""); settextstyle(SANS_SERIF_FONT, HORIZ_DIR, 4); outtextxy(32, 8, "SANS_SERIF_FONT"); settextstyle(DEFAULT_FONT, HORIZ_DIR, 4); outtextxy(32, 58, "DEFAULT_FONT"); settextstyle(GOTHIC_FONT, HORIZ_DIR, 4); outtextxy(32, 108, "GOTHIC_FONT"); settextstyle(SCRIPT_FONT, HORIZ_DIR, 4); outtextxy(32, 158, "SCRIPT_FONT"); getch(); closegraph(); }
If Else If Ladder in C/C++
The if...else statement executes two different codes depending upon whether the test expression is true or false. Sometimes, a choice has to be made from more than 2 possibilities. The if...else ladder allows you to check between multiple test expressions and execute different statements. In C/C++ if-else-if ladder helps user decide from among multiple options. The C/C++ if statements are executed from the top down. As soon as one of the conditions controlling the if is true, the statement associated with that if is executed, and the rest of the C else-if ladder is bypassed. If none of the conditions is true, then the final else statement will be executed.
Syntax of if...else Ladder in C++
if (Condition1) { Statement1; } else if(Condition2) { Statement2; } . . . else if(ConditionN) { StatementN; } else { Default_Statement; }
In the above syntax of if-else-if, if the Condition1 is TRUE then the Statement1 will be executed and control goes to next statement in the program following if-else-if ladder. If Condition1 is FALSE then Condition2 will be checked, if Condition2 is TRUE then Statement2 will be executed and control goes to next statement in the program following if-else-if ladder. Similarly, if Condition2 is FALSE then next condition will be checked and the process continues. If all the conditions in the if-else-if ladder are evaluated to FALSE, then Default_Statement will be executed.
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/* write a C program which demonstrate use of if-else-if ladder statement */ /* Program to Print Day Names using Else If Ladder in C++*/ #include <iostream> using namespace std; int main() { int day; cout << "Enter Day Number: "; cin >> day; cout << "Day is "; if (day == 1) cout << "Sunday" << endl; else if (day == 2) cout << "Monday" << endl; else if (day == 3) cout << "Tuesday" << endl; else if (day == 4) cout << "Wednesday" << endl; else if (day == 5) cout << "Thursday" << endl; else if (day == 6) cout << "Friday" << endl; else cout << "Saturday" << endl; return 0; }
floodfill() Function in C++
floodfill function is used to fill an enclosed area. Current fill pattern and fill color is used to fill the area.(x, y) is any point on the screen if (x,y) lies inside the area then inside will be filled otherwise outside will be filled, border specifies the color of boundary of area. To change fill pattern and fill color use setfillstyle.
Syntax for floodfill() Function in C++
#include <graphics.h> void floodfill(int x, int y, int border_color).
x
X coordinate of the point within the enclosed area to be filled
y
Y coordinate of the point within the enclosed area to be filled
border_color
specify the color int values corresponding to colors: • BLACK 0 • BLUE 1 • GREEN 2 • CYAN 3 • RED 4 • MAGENTA 5 • BROWN 6 • LIGHTGRAY 7 • DARKGRAY 8 • LIGHTBLUE 9 • LIGHTGREEN 10 • LIGHTCYAN 11 • LIGHTRED 12 • LIGHTMAGENTA 13 • YELLOW 14 • WHITE 15
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/* floodfill() fills an enclosed area on bitmap devices. (x,y) is a "seed point" within the enclosed area to be filled. The area bounded by the color border is flooded with the current fill pattern and fill color. If the seed point is within an enclosed area, the inside will be filled. If the seed is outside the enclosed area, the exterior will be filled. Use fillpoly instead of floodfill whenever possible so that you can maintain code compatibility with future versions. */ /* fill an enclosed area on bitmap devices by floodfill() function code example. */ #include <stdio.h> #include <conio.h> void main() { int d,m; int midx,midy; d=DETECT; initgraph(&d,&m,"c:\\tc\\bgi"); midx=getmaxx()/2; midy=getmaxy()/2; circle(midx,midy,50); floodfill(midx,midy,15); circle(midx+50,midy+100,80); floodfill(midx,midy,15); getch(); closegraph(); }
#include Directive in C++
#include is a way of including a standard or user-defined file in the program and is mostly written at the beginning of any C/C++ program. This directive is read by the preprocessor and orders it to insert the content of a user-defined or system header file into the following program. These files are mainly imported from an outside source into the current program. The process of importing such files that might be system-defined or user-defined is known as File Inclusion. This type of preprocessor directive tells the compiler to include a file in the source code program.
Syntax for #include Directive in C++
#include "user-defined_file"
Including using " ": When using the double quotes(" "), the preprocessor access the current directory in which the source "header_file" is located. This type is mainly used to access any header files of the user's program or user-defined files.
#include <header_file>
Including using <>: While importing file using angular brackets(<>), the the preprocessor uses a predetermined directory path to access the file. It is mainly used to access system header files located in the standard system directories. Header File or Standard files: This is a file which contains C/C++ function declarations and macro definitions to be shared between several source files. Functions like the printf(), scanf(), cout, cin and various other input-output or other standard functions are contained within different header files. So to utilise those functions, the users need to import a few header files which define the required functions. User-defined files: These files resembles the header files, except for the fact that they are written and defined by the user itself. This saves the user from writing a particular function multiple times. Once a user-defined file is written, it can be imported anywhere in the program using the #include preprocessor. • In #include directive, comments are not recognized. So in case of #include <a//b>, a//b is treated as filename. • In #include directive, backslash is considered as normal text not escape sequence. So in case of #include <a\nb>, a\nb is treated as filename. • You can use only comment after filename otherwise it will give error.
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/* using #include directive in C language */ #include <stdio.h> int main() { /* * C standard library printf function * defined in the stdio.h header file */ printf("I love you Clementine"); printf("I love you so much"); printf("HappyCodings"); return 0; }
What is an Multi-Dimensional Array
An array is a collection of data items, all of the same type, accessed using a common name. A one-dimensional array is like a list; A two dimensional array is like a table; The C++ language places no limits on the number of dimensions in an array, though specific implementations may. Some texts refer to one-dimensional arrays as vectors, two-dimensional arrays as matrices, and use the general term arrays when the number of dimensions is unspecified or unimportant.
Declaring Two-Dimensional Arrays
An array of arrays is known as 2D array. The two dimensional (2D) array in C++ programming is also known as matrix. A matrix can be represented as a table of rows and columns. In C/C++, we can define multi dimensional arrays in simple words as array of arrays. Data in multi dimensional arrays are stored in tabular form (in row major order). General form of declaring N-dimensional arrays is:
datatype arrayname[size1][size2]....[sizeN]; example: int 2d-array[8][16]; char letters[4][9]; float numbers[10][25];
Initializing Two-Dimensional Arrays
In the 1D array, we don't need to specify the size of the array if the declaration and initialization are being done simultaneously. However, this will not work with 2D arrays. We will have to define at least the second dimension of the array. The two-dimensional array can be declared and defined in the following way. Multidimensional arrays may be initialized by specifying bracketed values for each row. Following is an array with 3 rows and each row has 4 columns.
int numbers[3][4] = {{0, 1, 2, 3}, {4, 5, 6, 7}, {8, 9, 10, 11}};
Accessing Two-Dimensional Array Elements
Just like one-dimensional arrays, two-dimensional arrays also require indices to access the required elements. A row and a column index are needed to access a particular element; for nested loops, two indices (one to traverse the rows and the other to traverse the columns in each row) are required to print a two-dimensional array.
// an array with 3 rows and 2 columns. int x[3][2] = {{0,1}, {2,3}, {4,5}}; // output each array element's value for (int i = 0; i < 3; i++) { for (int j = 0; j < 2; j++) { cout << "Element at x[" << i << "][" << j << "]: "; cout << x[i][j]<<endl; } }
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/* multi-dimensional arrays in C++ language */ /* taking input for two dimensional array */ #include <iostream> using namespace std; int main() { int numbers[2][3]; cout << "Enter 6 numbers: " << endl; // Storing user input in the array for (int i = 0; i < 2; ++i) { for (int j = 0; j < 3; ++j) { cin >> numbers[i][j]; } } cout << "The numbers are: " << endl; // Printing array elements for (int i = 0; i < 2; ++i) { for (int j = 0; j < 3; ++j) { cout << "numbers[" << i << "][" << j << "]: " << numbers[i][j] << endl; } } return 0; }
setcolor() Function in C++
setcolor() function is used to set the foreground color in graphics mode. After resetting the foreground color you will get the text or any other shape which you want to draw in that color. setcolor sets the current drawing color to color, which can range from 0 to getmaxcolor. The current drawing color is the value to which pixels are set when lines, and so on are drawn. The drawing colors shown below are available for the CGA and EGA, respectively.
Syntax for setcolor() Function in C++
void setcolor(int color);
color
specify the color setcolor() functions contains only one argument that is color. It may be the color name enumerated in graphics.h header file or number assigned with that color. This function does not return any value. INT VALUES corresponding to Colors: • BLACK 0 • BLUE 1 • GREEN 2 • CYAN 3 • RED 4 • MAGENTA 5 • BROWN 6 • LIGHTGRAY 7 • DARKGRAY 8 • LIGHTBLUE 9 • LIGHTGREEN 10 • LIGHTCYAN 11 • LIGHTRED 12 • LIGHTMAGENTA 13 • YELLOW 14 • WHITE 15
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/* setcolor() function change the current drawing color in graphic mode. */ #include<stdio.h> #include<conio.h> #include<graphics.h> void main() { int gd=DETECT,gm; initgraph(&gd,&gm," "); setbkcolor(5);//set background color setcolor(11);//color of time settextstyle(4, HORIZ_DIR, 8);//font of time setcolor(GREEN); circle(320,240,100); setcolor(RED); outtextxy(320,80."It is circle"); getch(); closegraph(); }
clearviewport() Function in C++
clearviewport() function clears the current viewport. setviewport will create a new viewport by accepting left, top, right and bottom coordinates. clearviewport() function will erase the drawing done on the view port only and not the whole screen. Cleardevice is the function used to clear the whole screen with the background color.
Syntax for clearviewport() Function in C++
#include <graphics.h> void clearviewport(void);
This function does not return any value. This function is used to set the view port for the graphics output. It sets the new display area for the graphics output.
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/* setviewport() will create a new viewport by accepting left, top, right and bottom coordinates. The 5th argument for this function would be non zero, if you want to clip the drawing beyond this viewport. clearviewport() erases the viewport and moves the CP (current position) to home (0,0), relative to the viewport. */ /* erase the viewport and moves the current position to home (0,0) by clearviewport() function copde example. */ #include <graphics.h> #include <stdlib.h> #include <stdio.h> #include <conio.h> #define CLIP_ON 1 /* activates clipping in viewport */ int main(void) { /* request autodetection */ int gdriver = DETECT, gmode, errorcode, ht; /* initialize graphics and local variables */ initgraph(&gdriver, &gmode, ""); /* read result of initialization */ errorcode = graphresult(); if (errorcode != grOk) { /* an error occurred */ printf("Graphics error: %s\n", grapherrormsg(errorcode)); printf("Press any key to halt:"); getch(); exit(1); /* terminate with an error code */ } setcolor(getmaxcolor()); ht = textheight("W"); /* message in default full-screen viewport */ outtextxy(0, 0, "* <-- (0, 0) in default viewport"); /* create a smaller viewport */ setviewport(50, 50, getmaxx()-50, getmaxy()-50, CLIP_ON); /* display some messages */ outtextxy(0, 0, "* <-- (0, 0) in smaller viewport"); outtextxy(0, 2*ht, "Press any key to clear viewport:"); getch(); /* wait for a key */ clearviewport(); /* clear the viewport */ /* output another message */ outtextxy(0, 0, "Press any key to quit:"); /* clean up */ getch(); closegraph(); return 0; }
Goto Statement in C++
In C++, goto is a jump statement and sometimes also referred as unconditional jump statement. It can be used to jump from goto to a labeled statement within the same function. The target label must be within the same file and context. Please note that the use of goto statement is highly discouraged in any programming language because it makes difficult to trace the control flow of a program, making hard to understand and modify the program.
Syntax for Goto Statement in C++
goto label; ... ... ... label: statement;
label
the destination statement • The use of goto statement is highly discouraged as it makes the program logic very complex. • use of goto makes the task of analyzing and verifying the correctness of programs (particularly those involving loops) very difficult. • Use of goto can be simply avoided using break and continue statements.
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/* In C++ programming, the goto statement is used for altering the normal sequence of program execution by transferring control to some other part of the program. */ // This program calculates the average of numbers entered by the user. // If the user enters a negative number, it ignores the number and // calculates the average number entered before it. # include <iostream> using namespace std; int main() { float num, average, sum = 0.0; int i, n; cout << "Maximum number of inputs: "; cin >> n; for(i = 1; i <= n; ++i) { cout << "Enter n" << i << ": "; cin >> num; if(num < 0.0) { // Control of the program move to jump: goto jump; } sum += num; } jump: average = sum / (i - 1); cout << "\nAverage = " << average; return 0; }
strcpy() Function in C++
Copy string. Copies the C string pointed by source into the array pointed by destination, including the terminating null character (and stopping at that point). To avoid overflows, the size of the array pointed by destination shall be long enough to contain the same C string as source (including the terminating null character), and should not overlap in memory with source. strcpy() is a standard library function in C/C++ and is used to copy one string to another. In C it is present in string.h header file and in C++ it is present in cstring header file. It copies the whole string to the destination string. It replaces the whole string instead of appending it. It won't change the source string.
Syntax for strcpy() Function in C++
#include <cstring> char * strcpy ( char * destination, const char * source );
destination
Pointer to the destination array where the content is to be copied.
source
C string to be copied. destination is returned. After copying the source string to the destination string, the strcpy() function returns a pointer to the destination string. • This function copies the entire string to the destination string. It doesn't append the source string to the destination string. In other words, we can say that it replaces the content of destination string by the content of source string. • It does not affect the source string. The source string remains same after copying. • This function only works with C style strings and not C++ style strings i.e. it only works with strings of type char str[]; and not string s1; which are created using standard string data type available in C++ and not C.
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/* copy a character string from source to destination by strcpy() string function code example */ #include <cstring> #include <iostream> using namespace std; int main() { char src[20] = "I am the source."; // large enough to store content of src char dest[30] = "I am the destination."; cout << "dest[] before copy: " << dest << endl; // copy contents of src to dest strcpy(dest,src); cout << "dest[] after copy: " << dest; return 0; }
While Loop Statement in C++
In while loop, condition is evaluated first and if it returns true then the statements inside while loop execute, this happens repeatedly until the condition returns false. When condition returns false, the control comes out of loop and jumps to the next statement in the program after while loop. The important point to note when using while loop is that we need to use increment or decrement statement inside while loop so that the loop variable gets changed on each iteration, and at some point condition returns false. This way we can end the execution of while loop otherwise the loop would execute indefinitely. A while loop that never stops is said to be the infinite while loop, when we give the condition in such a way so that it never returns false, then the loops becomes infinite and repeats itself indefinitely.
Syntax for While Loop Statement in C++
while (condition) { // body of the loop }
• A while loop evaluates the condition • If the condition evaluates to true, the code inside the while loop is executed. • The condition is evaluated again. • This process continues until the condition is false. • When the condition evaluates to false, the loop terminates. Do not forget to increase the variable used in the condition, otherwise the loop will never end!
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/* While Loop Statement in C++ language */ // program to find the sum of positive numbers // if the user enters a negative number, the loop ends // the negative number entered is not added to the sum #include <iostream> using namespace std; int main() { int number; int sum = 0; // take input from the user cout << "Enter a number: "; cin >> number; while (number >= 0) { // add all positive numbers sum += number; // take input again if the number is positive cout << "Enter a number: "; cin >> number; } // display the sum cout << "\nThe sum is " << sum << endl; return 0; }
rand() Function in C++
Generate random number. Returns a pseudo-random integral number in the range between 0 and RAND_MAX. This number is generated by an algorithm that returns a sequence of apparently non-related numbers each time it is called. This algorithm uses a seed to generate the series, which should be initialized to some distinctive value using function srand. RAND_MAX is a constant defined in <cstdlib>.
Syntax for rand() Function in C++
#include <cstdlib> int rand();
The rand() function in C++ is used to generate random numbers; it will generate the same number every time we run the program. In order to seed the rand() function, srand(unsigned int seed) is used. The srand() function sets the initial point for generating the pseudo-random numbers. The rand() function generates numbers randomly. When execute the rand() function in a program, the same random number gets represented. The srand() function along with the rand() function generates random numbers at compile time. The srand() function does not return any value while the rand() function returns the random number generated by it. C++ supports a wide range of powerful tools to generate random and pseudo-random numbers (see <random> for more info). The function accepts no parameter(s). The standard practice is to use the return value of time(0) function as the seed. Function returns an integer value between 0 and RAND_MAX. If random numbers are generated with rand() without first calling srand(), your program will create the same sequence of numbers each time it runs.
Compatibility
In C, the generation algorithm used by rand is guaranteed to only be advanced by calls to this function. In C++, this constraint is relaxed, and a library implementation is allowed to advance the generator on other circumstances (such as calls to elements of <random>).
Data races
The function accesses and modifies internal state objects, which may cause data races with concurrent calls to rand or srand. Some libraries provide an alternative function that explicitly avoids this kind of data race: rand_r (non-portable). C++ library implementations are allowed to guarantee no data races for calling this function.
Exceptions
No-throw guarantee: this function never throws exceptions.
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/* generate random number by rand() function code example */ #include <iostream> #include <cstdlib> #include <ctime> int main() { using namespace std; time_t qTime; time(&qTime); // Use a varying seed, like time, to generate new sequences. srand(qTime); cout << "A varying sequence of random numbers:" << endl; for (unsigned int uiIndex = 0; uiIndex < 10; ++uiIndex) { cout << " " << rand(); } cout << endl; // Use a constant with srand to generate the same sequence. srand(2); cout << "A fixed sequence of random numbers:" << endl; for (unsigned int uiIndex = 0; uiIndex < 10; ++uiIndex) { cout << " " << rand(); } cout << endl; cout << "The generated range is 0 to " << RAND_MAX << endl; return 0; }
rectangle() Function in C++
rectangle() is used to draw a rectangle. Coordinates of left top and right bottom corner are required to draw the rectangle. left specifies the X-coordinate of top left corner, top specifies the Y-coordinate of top left corner, right specifies the X-coordinate of right bottom corner, bottom specifies the Y-coordinate of right bottom corner.
Syntax for rectangle() Function in C++
rectangle(int left, int top, int right, int bottom);
left
X coordinate of top left corner.
top
Y coordinate of top left corner.
right
X coordinate of bottom right corner.
bottom
Y coordinate of bottom right corner. To create a rectangle, you have to pass the four parameters in this function. The two parameters represent the left and top upper left corner. Similarly, the right bottom parameter represents the lower right corner of the rectangle. This function does not return any value.
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/* function rectangle() draws a rectangle in graphic mode. */ int main() { // location of left, top, right, bottom int left = 150, top = 150; int right = 450, bottom = 450; // initgraph initializes the graphics system // by loading a graphics driver from disk initgraph(&gd, &gm, ""); // rectangle function rectangle(left, top, right, bottom); left = 200, = 250; right = 150, = 300; rectangle(left, top, right, bottom); left = 100, = 200; right = 450, = 100; rectangle(left, top, right, bottom); getch(); return 0; }
exit() Function in C++
The exit function terminates the program normally. Automatic objects are not destroyed, but static objects are. Then, all functions registered with atexit are called in the opposite order of registration. The code is returned to the operating system. An exit code of 0 or EXIT_SUCCESS means successful completion. If code is EXIT_FAILURE, an indication of program failure is returned to the operating system. Other values of code are implementation-defined.
Syntax for exit() Function in C++
void exit (int status);
status
Status code. If this is 0 or EXIT_SUCCESS, it indicates success. If it is EXIT_FAILURE, it indicates failure. Calls all functions registered with the atexit() function, and destroys C++ objects with static storage duration, all in last-in-first-out (LIFO) order. C++ objects with static storage duration are destroyed in the reverse order of the completion of their constructor. (Automatic objects are not destroyed as a result of calling exit().) Functions registered with atexit() are called in the reverse order of their registration. A function registered with atexit(), before an object obj1 of static storage duration is initialized, will not be called until obj1's destruction has completed. A function registered with atexit(), after an object obj2 of static storage duration is initialized, will be called before obj2's destruction starts. Normal program termination performs the following (in the same order): • Objects associated with the current thread with thread storage duration are destroyed (C++11 only). • Objects with static storage duration are destroyed (C++) and functions registered with atexit are called. • All C streams (open with functions in <cstdio>) are closed (and flushed, if buffered), and all files created with tmpfile are removed. • Control is returned to the host environment. Note that objects with automatic storage are not destroyed by calling exit (C++). If status is zero or EXIT_SUCCESS, a successful termination status is returned to the host environment. If status is EXIT_FAILURE, an unsuccessful termination status is returned to the host environment. Otherwise, the status returned depends on the system and library implementation. Flushes all buffers, and closes all open files. All files opened with tmpfile() are deleted. Returns control to the host environment from the program. exit() returns no values.
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/* terminate the process normally, performing the regular cleanup for terminating programs by exit() function code example */ #include<iostream> using namespace std; int main() { int i; cout<<"Enter a non-zero value: "; //user input cin>>i; if(i) // checks whether the user input is non-zero or not { cout<<"Valid input.\n"; } else { cout<<"ERROR!"; //the program exists if the value is 0 exit(0); } cout<<"The input was : "<<i; }
main() Function in C++
A program shall contain a global function named main, which is the designated start of the program in hosted environment. main() function is the entry point of any C++ program. It is the point at which execution of program is started. When a C++ program is executed, the execution control goes directly to the main() function. Every C++ program have a main() function.
Syntax for main() Function in C++
void main() { ............ ............ }
void
void is a keyword in C++ language, void means nothing, whenever we use void as a function return type then that function nothing return. here main() function no return any value.
main
main is a name of function which is predefined function in C++ library. In place of void we can also use int return type of main() function, at that time main() return integer type value. 1) It cannot be used anywhere in the program a) in particular, it cannot be called recursively b) its address cannot be taken 2) It cannot be predefined and cannot be overloaded: effectively, the name main in the global namespace is reserved for functions (although it can be used to name classes, namespaces, enumerations, and any entity in a non-global namespace, except that a function called "main" cannot be declared with C language linkage in any namespace). 3) It cannot be defined as deleted or (since C++11) declared with C language linkage, constexpr (since C++11), consteval (since C++20), inline, or static. 4) The body of the main function does not need to contain the return statement: if control reaches the end of main without encountering a return statement, the effect is that of executing return 0;. 5) Execution of the return (or the implicit return upon reaching the end of main) is equivalent to first leaving the function normally (which destroys the objects with automatic storage duration) and then calling std::exit with the same argument as the argument of the return. (std::exit then destroys static objects and terminates the program). 6) (since C++14) The return type of the main function cannot be deduced (auto main() {... is not allowed). 7) (since C++20) The main function cannot be a coroutine.
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/* simple code example by main() function in C++ */ #include <iostream> using namespace std; int main() { int day = 4; switch (day) { case 1: cout << "Monday"; break; case 2: cout << "Tuesday"; break; case 3: cout << "Wednesday"; break; case 4: cout << "Thursday"; break; case 5: cout << "Friday"; break; case 6: cout << "Saturday"; break; case 7: cout << "Sunday"; break; } return 0; }
kbhit() Function in C++
The kbhit is basically the Keyboard Hit. This function is present at conio.h header file. So for using this, we have to include this header file into our code. The functionality of kbhit() is that, when a key is pressed it returns nonzero value, otherwise returns zero. kbhit() is used to determine if a key has been pressed or not. If a key has been pressed then it returns a non zero value otherwise returns zero.
Syntax for kbhit() Function in C++
#include <conio.h> int kbhit();
Function returns true (non-zero) if there is a character in the input buffer, otherwise false. Note : kbhit() is not a standard library function and should be avoided.
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/* kbhit() function is not defined as part of the ANSI C/C++ standard. It is generally used by Borland's family of compilers. It returns a non-zero integer if a key is in the keyboard buffer. It will not wait for a key to be pressed. */ // C++ program code example to fetch key pressed using kbhit() #include <conio.h> #include <iostream> int main() { char ch; while (1) { if (kbhit) { // Stores the pressed key in ch ch = getch(); // Terminates the loop // when escape is pressed if (int(ch) == 27) break; cout << "Key pressed= " << ch; } } return 0; }


First think what is the factorial of a number? How 'mathematically' it can be calculated. If you got this info then it will be very easier to make a C++ code logic to find the "Factorial".
The first program uses temporary variable to swap numbers, whereas the second program doesn't use temporary variables. To perform 'swapping' in above example, three variables