C++ do-while loop

do-while loop

The do-while loop is an exit-controlled loop. In do-while loop, the condition is evaluated at the bottom of the loop after executing the body of the loop. This means that the body of the loop is executed at least once, even when the condition evaluates false during the first iteration.

The do-while loop syntax is:

do

{

      Body of the loop;

} while(condition);

The flow control and flow chart do-while loop is shown below

Flowchart 10.8 : do-while loop control flow and do-while loop flowchart

Illustration 10.16 C++ program to display number from 10 to 1 using do-while loop

#include <iostream>

using namespace std;

int main ()

{

int n = 10;

do

{

      cout<<n<<", ";

      n--;

}while (n>0) ;

}

Output

10, 9, 8, 7, 6, 5, 4, 3, 2, 1

In the above program, the integer variable n is initialized to 10. Next the value of n is displayed as 10 and n is decremented by 1. Now, the condition is evaluated, since 9 > 0, again 9 is displayed and n is decremented to 8. This continues, until n becomes equal to 0, at which point, the condition n > 0 will evaluate to false and the do-while loop terminates.