C++ Do While Loop

The do/while loop in C++ is a variation of the while loop that ensures the code block executes at least once before the condition is checked. This makes it useful for situations where the initial execution must occur regardless of the condition’s result.

How the do/while Loop Works

Unlike the while loop, which checks the condition before running its block, the do/while loop executes the block first and evaluates the condition afterwards.

Syntax

do {
    // Code block executes at least once
} while (condition);

Example: Counting Laps on a Track

This program counts laps and guarantees the first lap gets counted, even if the condition is false.

#include <iostream>
using namespace std;

int main() {
    int lap = 0;

    do {
        cout << "Lap number: " << lap << "\n";
        lap++;
    } while (lap < 3);  // Loop repeats until lap is 3 or greater

    return 0;
}

How the Example Works

• The variable lap starts at 0.
• The loop runs once, prints the lap number, and increments lap.
• After the code block executes, the condition (lap < 3) is checked. If true, the loop repeats.
• Once lap reaches 3, the condition becomes false, and the loop stops.