do-while loop in C++ programming language

 do-while loop in C++ programming language

In this tutorial, we will discuss do-while loop C++ programming language.

The do while loop is functioning similar while loop but there is a small difference. The body of the do while loop is executed at least once before the test expression is evaluated.

Syntax

do{
//codes inside the body of loop
}while(testExpression);

Flow diagram

How do-while loops work

• The body of the do while loop is executed once only
• Then the test (boolean) expression is evaluated
• If the test expression is true the codes inside the body of the loop are executed.
• This process continues until the test expression becomes false
• finnally, when the test expression is false the control exits from the loop

Do while loop Example

Program 1

This program displays natural numbers from 1 to n using do while loop

#include <iostream>
#include <conio.h>
using namespace std;

int main()
{
    int i=1;
    while(i<=10){
    cout << i << endl;
    i++;
    }
    getch();
    return 0;
}

When the above code is executed it produces the following the result

1
2
3
4
5
6
7
8
9
10

Program 2

This program allows the user to enter some numbers then it uses to find the sum of given numbers until the user enters zero

#include <iostream>
using namespace std;

int main() {
float number, sum = 0.0;

do {
cout<<"Enter a number: ";
cin>>number;
sum += number;
}
while(number != 0.0);

cout<<"Total sum = "<<sum;

return 0;
}

When the above code is executed it produces the following the result

#include <iostream>
#include <conio.h>
using namespace std;

int main()
{
    int num,fact=1,i=1;

    cout << "Enter the number" << endl;
    cin>>num;
  do{
    fact=fact*i;
    i++;
  }
    while(i<=num);
    cout<<"The factorial of "<<num<<" : "<<fact;
    getch();
    return 0;
}

When the above code is executed it produces the following the result

Enter the number
5
The factorial of 5: 120