# C++ Programming Code Examples

## C++ > Algorithms Code Examples

### Program To Implement Tower Of Hanoi Alogithm Using Recursion.

/* Program To Implement Tower Of Hanoi Alogithm Using Recursion. This program shows the movements of disk from one tower to another when a key is pressed. */ #include<iostream.h> #include<stdio.h> #include<conio.h> class tower { int *t1,*t2,*t3; int x,y,z; public: void disp_tower(); void move_disk(int tx,int ty); void toh(int n,int a,int b,int c); tower(int no); ~tower(); }; tower :: tower(int no) { t1 = new int[no+1]; t2 = new int[no+1]; t3 = new int[no+1]; x = no; y = z = 0; for(int i=0,j=no ; i<no ; i++,j--) { t1[i] = j; t2[i] = t2[i] = 0; } t1[no] = t2[no] = t3[no] = 0; } tower :: ~tower() { delete []t1; delete []t2; delete []t3; } void tower :: disp_tower() { clrscr(); cout<<" X :: "; for(int i=0;i<x;i++) { cout<<" "<<t1[i]; } cout<<" Y :: "; for(i=0;i<y;i++) { cout<<" "<<t2[i]; } cout<<" Z :: "; for(i=0;i<z;i++) { cout<<" "<<t3[i]; } getch(); } void tower :: toh(int n,int tx,int ty,int tz) //x to y using z { if(n>=1) { toh(n-1,tx,tz,ty); move_disk(tx,ty); //x to y disp_tower(); toh(n-1,tz,ty,tx); } } void tower :: move_disk(int tx,int ty) { switch(tx) { case 1: { if(ty==2) t2[y++] = t1[--x]; else t3[z++] = t1[--x]; }break; case 2: { if(ty==1) t1[x++] = t2[--y]; else t3[z++] = t2[--y]; }break; case 3: { if(ty==1) t1[x++] = t3[--z]; else t2[y++] = t3[--z]; }break; }//end of switch } //------------------------------------------------------------------------ --- int main(void) { clrscr(); cout<<"Enter the no. of disks::"; int no; cin>>no; tower obj(no); obj.disp_tower(); obj.toh(no,1,2,3); getch(); return 0; } //------------------------------------------------------------------------ ---

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.

The cin object is used to accept input from the standard input device i.e. keyboard. It is defined in the iostream header file. C++ cin statement is the instance of the class istream and is used to read input from the standard input device which is usually a keyboard. The extraction operator(>>) is used along with the object cin for reading inputs. The extraction operator extracts the data from the object cin which is entered using the keyboard. The "c" in cin refers to "character" and "in" means "input". Hence cin means "character input". The cin object is used along with the extraction operator >> in order to receive a stream of characters.

#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.

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. • 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

Deallocate storage space. Default deallocation functions (single-object form). A delete operator is used to deallocate memory space that is dynamically created using the new operator, calloc and malloc() function, etc., at the run time of a program in C++ language. In other words, a delete operator is used to release array and non-array (pointer) objects from the heap, which the new operator dynamically allocates to put variables on heap memory. We can use either the delete operator or delete [ ] operator in our program to delete the deallocated space. A delete operator has a void return type, and hence, it does not return a value.

The cout is a predefined object of ostream class. It is connected with the standard output device, which is usually a display screen. The cout is used in conjunction with stream insertion operator (<<) to display the output on a console. On most program environments, the standard output by default is the screen, and the C++ stream object defined to access it is cout. The "c" in cout refers to "character" and "out" means "output". Hence cout means "character output". The cout object is used along with the insertion operator << in order to display a stream of characters.

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.

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.

Allocate storage space. Default allocation functions (single-object form). A new operator is used to create the object while a delete operator is used to delete the object. When the object is created by using the new operator, then the object will exist until we explicitly use the delete operator to delete the object. Therefore, we can say that the lifetime of the object is not related to the block structure of the program.

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, 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.

In C++, constructor is a special method which is invoked automatically at the time of object creation. It is used to initialize the data members of new object generally. The constructor in C++ has the same name as class or structure. Constructors are special class functions which performs initialization of every object. The Compiler calls the Constructor whenever an object is created. Constructors initialize values to object members after storage is allocated to the object. Whereas, Destructor on the other hand is used to destroy the class object. • Default Constructor: A constructor which has no argument is known as default constructor. It is invoked at the time of creating object.

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.

A destructor is a special member function that works just opposite to constructor, unlike constructors that are used for initializing an object, destructors destroy (or delete) the object. Destructors in C++ are members functions in a class that delete an object. They are called when the class object goes out of scope such as when the function ends, the program ends, a delete variable is called etc. Destructors are different from normal member functions as they don't take any argument and don't return anything. Also, destructors have the same name as their class and their name is preceded by a tilde(~).

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. 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.

The main purpose of C++ programming is to add object orientation to the C programming language and classes are the central feature of C++ that supports object-oriented programming and are often called user-defined types. A class is used to specify the form of an object and it combines data representation and methods for manipulating that data into one neat package. The data and functions within a class are called members of the class.

Function returns true if the number passed to the function is a 'prime number', returns false if the number passed is not a 'prime number'. The appropriate message is printed from the

Finding the smallest item in the tree. Return smallest item or 'INFINITY' if empty. Find the largest item in the tree. "Return the Largest" item or INFINITY if empty. Find item x in the

First we have to clear about what is transpose of a matrix. Its to replace the number of rows with number of colums, vice versa to make a new matrix. So for example if a matrix 'A' has