The while loop - loops - repetition - control structures

The for loop does something we know in advance that how many times a loop has to be executed.

But if you don’t know that how many times your loop is going to be run then while loop is the choice.

Syntax

While(condition)

{

     Statement(s);

}

The flow diagram for it is:

Let’s have a look at an example:

#include <iostream>

using namespace std;

int main(){

int n = 99;     // make sure n isn’t initialized to 0

while( n != 0 )   // loop until n is 0

cin >> n;      // read a number into n

cout << endl;

return 0;

}

Here’s some sample output. The user enters numbers, and the loop continues until 0 is entered, at which point the loop ends and the program is terminated.

Output:

1 27 33 144 9 0