C++ While Loop: Entry-Controlled Iteration, Syntax & Practical Drills

A while loop is an entry-controlled loop that repeatedly executes a target statement block as long as a given boolean condition remains true. It is most appropriate when the total number of iterations is not known in advance.

Syntax and Flowchart Logic

while (condition) {
    // Statements executed repeatedly
    // Update expression (increment/decrement)
}

Classic University Lab Problem: Reverse a Number

#include <iostream>

int main() {
    int num = 4589;
    int reversedNum = 0;

    std::cout << "Original Number: " << num << "\n";

    while (num > 0) {
        int remainder = num % 10;                     // Extract last digit
        reversedNum = (reversedNum * 10) + remainder;  // Append digit
        num /= 10;                                    // Remove last digit
    }

    std::cout << "Reversed Number: " << reversedNum << "\n";
    return 0;
}