`do` — C++ Keyword

The do keyword in C++: executes a body at least once, then repeats while a condition is true.

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`do`

Executes the body at least once, then repeats as long as the condition is true. Unlike while, the condition is checked after each iteration.

Syntax

do statement while (condition);

Example

#include <print>

int main() {
    int n = 0;

    do {
        std::print("{} ", n);
        ++n;
    } while (n < 5);
    // Output: 0 1 2 3 4

    std::println();

    // Guarantees at least one prompt even if input is immediately valid
    int value;
    do {
        std::println("Enter a positive number:");
        value = 7;  // simulated input
    } while (value <= 0);
}

Notes

The semicolon after while (condition) is mandatory.
Most useful when the loop body must execute before the condition can be evaluated.
cppreference: do-while

int main() { // Pick one facility from this reference page. // Write the smallest program that exercises its main precondition, // complexity rule, or lifetime constraint before scaling up. return 0; }