do-while loop in C++

C++ do-while Loop: Syntax and Examples

The do-while loop is a looping statement in C++ that executes the loop body at least once, even if the condition is false. This is because the condition is checked after executing the loop body.

Syntax

do {

// statements to be executed

} while (condition);

Key Points

• The semicolon (;) after while(condition) is mandatory.
• Loop body executes minimum one time
• Condition is checked after execution
• Useful when at least one execution is required (menus, input validation)

Example 1: Print Numbers from 1 to 5

#include <iostream>

using namespace std;

int main() {

    int i = 1;

    do {

        cout << i << " ";

        i++;

    } while (i <= 5);

    return 0;

}

Output:

1 2 3 4 5

Example 2: Sum of First 3 Numbers

#include <iostream>

using namespace std;

int main() {

    int i = 1, sum = 0;

    do {

        sum = sum + i;

        i++;

    } while (i <= 3);

    cout << "Sum = " << sum;

    return 0;

}

Output:

Sum = 6

Example 3: C++ program to print Z to A using do..while loop.

#include<iostream>

using namespace std;

int main()

{

  char ch='Z';

  do

  {

    cout << ch;

  ch = ch - 1;

  }

  while(ch >= 'A');

  return 0;

}

Output:

ZYXWVUTSRQPONMLKJIHGFEDCBA

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