While Loop

Overview

A while loop repeatedly executes a block of code as long as a specified condition is true. It is best used when the number of iterations is unknown beforehand.

Syntax

cpp

int count = 0;

while (count < 5) {
    cout << count << " ";
    count++; // Don't forget to update the condition!
}

Common Pitfalls

Creating an infinite loop by forgetting to update the loop variable inside the loop body.

Interview Tips

Be prepared to explain when to choose a `while` loop over a `for` loop (use `while` when reading files, network streams, or taking user input until a sentinal value is hit).

Real-World Example

Extracting digits from a number.

example

cpp

#include <iostream>
using namespace std;

int main() {
    int n = 1234;
    int reversed = 0;
    
    while (n > 0) {
        int digit = n % 10;
        reversed = (reversed * 10) + digit;
        n /= 10;
    }
    
    cout << "Reversed: " << reversed << endl;
    return 0;
}

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