C++ While loop

In C++, while loop causes a program to repeat a group of statements or code block as long a starting condition remains true. They are executed repeatedly until the expression is false. Note that the condition is only checked at the start of each iteration (loop).

Syntax

The while keyword is followed by an expression in parentheses. If the expression is true, the statements inside the loop block are executed.

while(condition){  
//code to be executed  
}

Flowchart:

Cpp While loop 1
Example

Let's see a simple example of while loop to print table of 1.

snippet
#include <iostream>
using namespace std;
int main() {       
 int i=1;    
         while(i<=10) 
       {    
            cout<<i <<"\n";  
            i++;
          }     
    }
Output
1 2 3 4 5 6 7 8 9 10

Nested while loop

In C++, we can use while loop inside the body of another while loop, it is known as nested while loop. The nested while loop is executed fully when outer loop is executed once.

Example

Let's see a simple example of nested while loop in C++ programming language.

snippet
#include <iostream>
using namespace std;
int main () {
        int i=1;    
          while(i<=3)   
          {  
              int j = 1;  
              while (j <= 3)  
{    
            cout<<i<<" "<<j<<"\n";    
            j++;
          }   
           i++;
        }
    }
Output
1 1 1 2 1 3 2 1 2 2 2 3 3 1 3 2 3 3

Infinitive while Loop

A while loop executes as long as its condition is true. We can also create infinite while loop by passing true as the test condition.

Example
snippet
#include <iostream>
using namespace std;
int main () {
        while(true)
          {  
                  cout<<"Infinitive While Loop";  
          }  
    }
Output
Infinitive While Loop Infinitive While Loop Infinitive While Loop Infinitive While Loop Infinitive While Loop ctrl+c
Note
Infinite loops such as while(true) can cause a program to run forever if the exit condition is never reached. To end execution of a such program that isn’t ending on its own press Ctrl+C.
Related Tutorial
Follow Us
https://www.facebook.com/Rookie-Nerd-638990322793530 https://twitter.com/RookieNerdTutor https://plus.google.com/b/117136517396468545840 #
Contents +