C++ Programming Code Examples

/* program to Solve Tower of Hanoi Problem using Stacks This C++ program displays the iterative solution to the Tower of Hanoi problem. Tower Of Hanoi consists of three rods and a number of disks of different sizes which can slide onto any rod. The puzzle starts with the disks in a neat stack in ascending order of size on one rod, the smallest at the top, thus making a conical shape. The objective of the puzzle is to move the entire stack to another rod, obeying the following simple rules: Only one disk may be moved at a time. Each move consists of taking the upper disk from one of the stacks and placing it on top of another stack. No disk may be placed on top of a smaller disk. C++ Program to Traverse a Graph using DFS */ #include<stdio.h> #include<conio.h> #include<iostream> #include<math.h> using namespace std; struct node1 { int data1; node1 *next1; }*top1 = NULL, *p1 = NULL, *np1 = NULL; struct node2 { int data2; node2 *next2; }*top2 = NULL, *p2 = NULL, *np2 = NULL; struct node3 { int data3; node3 *next3; }*top3 = NULL, *p3 = NULL, *np3 = NULL; void push1(int data) { np1 = new node1; np1->data1 = data; np1->next1 = NULL; if (top1 == NULL) { top1 = np1; } else { np1->next1 = top1; top1 = np1; } } int pop1() { int b = 999; if (top1 == NULL) { return b; } else { p1 = top1; top1 = top1->next1; return(p1->data1); delete(p1); } } void push2(int data) { np2 = new node2; np2->data2 = data; np2->next2 = NULL; if (top2 == NULL) { top2 = np2; } else { np2->next2 = top2; top2 = np2; } } int pop2() { int b = 999; if (top2 == NULL) { return b; } else { p2 = top2; top2 = top2->next2; return(p2->data2); delete(p2); } } void push3(int data) { np3 = new node3; np3->data3 = data; np3->next3 = NULL; if (top3 == NULL) { top3 = np3; } else { np3->next3 = top3; top3 = np3; } } int pop3() { int b = 999; if (top3 == NULL) { return b; } else { p3 = top3; top3 = top3->next3; return(p3->data3); delete(p3); } } int top_of_stack() { if (top1 != NULL && top1->data1 == 1 ) { return 1; } else if (top2 != NULL && top2->data2 == 1) { return 2; } else if (top3 != NULL && top3->data3 == 1) { return 3; } } void display1() { cout<<endl; node1 *p1; p1 = top1; cout<<"Tower1-> "<<"\t"; while (p1 != NULL) { cout<<p1->data1<<"\t"; p1 = p1->next1; } cout<<endl; } void display2() { node2 *p2; p2 = top2; cout<<"Tower2-> "<<"\t"; while (p2 != NULL) { cout<<p2->data2<<"\t"; p2 = p2->next2; } cout<<endl; } void display3() { node3 *p3; p3 = top3; cout<<"Tower3-> "<<"\t"; while (p3 != NULL) { cout<<p3->data3<<"\t"; p3 = p3->next3; } cout<<endl; cout<<endl; } void toh(int n) { int i, x, a, b; for (i = 0; i < (pow(2,n)); i++) { display1(); display2(); display3(); x = top_of_stack(); if (i % 2 == 0) { if (x == 1) { push3(pop1()); } else if (x == 2) { push1(pop2()); } else if (x == 3) { push2(pop3()); } } else { if (x == 1) { a = pop2(); b = pop3(); if (a < b && b != 999) { push3(b); push3(a); } else if (a > b && a != 999) { push2(a); push2(b); } else if (b == 999) { push3(a); } else if (a == 999) { push2(b); } } else if (x == 2) { a = pop1(); b = pop3(); if (a < b && b != 999) { push3(b); push3(a); } else if (a > b && a != 999) { push1(a); push1(b); } else if (b == 999) { push3(a); } else if (a == 999) { push1(b); } } else if (x == 3) { a = pop1(); b = pop2(); if (a < b && b != 999) { push2(b); push2(a); } else if (a > b && a != 999) { push1(a); push1(b); } else if (b == 999) { push2(a); } else if (a == 999) { push1(b); } } } } } int main() { int n, i; cout<<"enter the number of disks\n"; cin>>n; for (i = n; i >= 1; i--) { push1(i); } toh(n); getch(); }

/* 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; }

/* deallocate storage space by delete operator */ #include <iostream> using namespace std; int main () { // declaration of variables int *ptr1, *ptr2, sum; // allocated memory space using new operator ptr1 = new int; ptr2 = new int; cout << " Enter first number: "; cin >> *ptr1; cout << " Enter second number: "; cin >> *ptr2; sum = *ptr1 + *ptr2; cout << " Sum of pointer variables = " << sum; // delete pointer variables delete ptr1; delete ptr2; return 0; }

/* 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; }

/* C++ allows us to allocate the memory of a variable or an array in run time. This is known as dynamic memory allocation. The new operator denotes a request for memory allocation on the Free Store. If sufficient memory is available, new operator initializes the memory and returns the address of the newly allocated and initialized memory to the pointer variable. */ /* Allocate storage space by operator new */ // C++ program code example to illustrate dynamic allocation and deallocation of memory using new and delete #include <iostream> using namespace std; int main () { // Pointer initialization to null int* p = NULL; // Request memory for the variable // using new operator p = new(nothrow) int; if (!p) cout << "allocation of memory failed\n"; else { // Store value at allocated address *p = 29; cout << "Value of p: " << *p << endl; } // Request block of memory // using new operator float *r = new float(75.25); cout << "Value of r: " << *r << endl; // Request block of memory of size n int n = 5; int *q = new(nothrow) int[n]; if (!q) cout << "allocation of memory failed\n"; else { for (int i = 0; i < n; i++) q[i] = i+1; cout << "Value store in block of memory: "; for (int i = 0; i < n; i++) cout << q[i] << " "; } // freed the allocated memory delete p; delete r; // freed the block of allocated memory delete[] q; return 0; }

/* Standard Input Stream (cin) in C++ language */ // cin with Member Functions #include <iostream> using namespace std; int main() { char name[20], address[20]; cout << "Name: "; // use cin with getline() cin.getline(name, 20); cout << "Address: "; cin.getline(address, 20); cout << endl << "You entered " << endl; cout << "Name = " << name << endl; cout << "Address = " << address; return 0; }

/* standard output stream (cout) in C++ language */ #include <iostream> using namespace std; int main() { string str = "Do not interrupt me"; char ch = 'm'; // use cout with write() cout.write(str,6); cout << endl; // use cout with put() cout.put(ch); return 0; }

/* 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; }

/* 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; }

/* 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; }

/* Structure is a collection of variables of different data types under a single name. It is similar to a class in that, both holds a collecion of data of different data types. */ #include <iostream> using namespace std; struct Person { char name[50]; int age; float salary; }; int main() { Person p1; cout << "Enter Full name: "; cin.get(p1.name, 50); cout << "Enter age: "; cin >> p1.age; cout << "Enter salary: "; cin >> p1.salary; cout << "\nDisplaying Information." << endl; cout << "Name: " << p1.name << endl; cout <<"Age: " << p1.age << endl; cout << "Salary: " << p1.salary; return 0; }

/* 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() }

/* get base raised to the power exponent by pow() function */ // CPP program code example to illustrate power function #include <bits/stdc++.h> using namespace std; int main() { double x = 6.1, y = 4.8; // Storing the answer in result. double result = pow(x, y); // printing the result upto 2 // decimal place cout << fixed << setprecision(2) << result << endl; return 0; }

/* Stack in C++ language */ #include <iostream> #include <stack> using namespace std; void newstack(stack <int> ss) { stack <int> sg = ss; while (!sg.empty()) { cout << '\t' << sg.top(); sg.pop(); } cout << '\n'; } int main () { stack <int> newst; newst.push(55); newst.push(44); newst.push(33); newst.push(22); newst.push(11); cout << "The stack newst is : "; newstack(newst); cout << "\n newst.size() : " << newst.size(); cout << "\n newst.top() : " << newst.top(); cout << "\n newst.pop() : "; newst.pop(); newstack(newst); return 0; }

/* 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; }

/* Standard end line (endl) in C++ language */ //The header file iostream is imported to enable us to use cout in the program #include <iostream> //a namespace called std is defined using namespace std; //main method is called int main( ) { //cout is used to output the statement cout<< "Welcome to "; //cout is used to output the statement along with endl to start the next statement in the new line and flush the output stream cout<< "C#"<<endl; //cout is used to output the statement along with endl to start the next statement in the new line and flush the output stream cout<< "Learning is fun"<<endl; }

/* namespaces in C++ language */ // A C++ code to demonstrate that we can define // methods outside namespace. #include <iostream> using namespace std; // Creating a namespace namespace ns { void display(); class happy { public: void display(); }; } // Defining methods of namespace void ns::happy::display() { cout << "ns::happy::display()\n"; } void ns::display() { cout << "ns::display()\n"; } // Driver code int main() { ns::happy obj; ns::display(); obj.display(); return 0; }