Do-While Loop

Overview

The do-while loop is a variant of the while loop that evaluates its condition at the end of the block. This guarantees the loop body executes *at least once*.

Syntax

cpp

int i = 0;

do {
    cout << "This prints at least once.";
    i++;
} while (i < 0); // Condition is false, but loop ran once.

Common Pitfalls

Forgetting the semicolon `;` after the `while(condition)` statement. It is required in a do-while loop.

Interview Tips

Know that the classic use case for a do-while loop is prompting a user for input and validating it.

Real-World Example

Prompting user for valid input.

example

cpp

#include <iostream>
using namespace std;

int main() {
    int choice;
    do {
        cout << "Enter a positive number: ";
        cin >> choice;
    } while (choice <= 0);
    
    cout << "You entered: " << choice << endl;
    return 0;
}

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