Loops

If variables are the "memory" and conditionals are the "brain," then loops are the "muscles" of your program. Loops allow you to repeat a block of code multiple times without rewriting it. This is essential for processing lists, repeating game cycles, or validating user input.

In C++, we have three primary types of loops.

1. The for Loop

Best used when you know exactly how many times you want to repeat something (e.g., "count to 10").

• Syntax: for (initialization; condition; increment)

2. The while Loop

Best used when you want to repeat something until a condition changes, but you don't know exactly when that will happen (e.g., "keep asking for a password until it's correct").

• Syntax: while (condition) { // code }

3. The do-while Loop

Similar to the while loop, but it guarantees the code runs at least once before checking the condition.

Code Example: Counting and Validation

This program uses a for loop to print a multiplication table and a while loop to force a user to enter a positive number.

#include <iostream>
using namespace std;

int main() {
    // 1. FOR LOOP: Multiplication Table for 5
    cout << "--- Table of 5 ---" << endl;
    for (int i = 1; i <= 5; i++) {
        cout << "5 x " << i << " = " << (5 * i) << endl;
    }

    // 2. WHILE LOOP: Input Validation
    int secretPin = 1234;
    int enteredPin;

    cout << "\n--- Security Check ---" << endl;
    cout << "Enter your PIN: ";
    cin >> enteredPin;

    while (enteredPin != secretPin) {
        cout << "Wrong PIN! Try again: ";
        cin >> enteredPin;
    }

    cout << "Access Granted!" << endl;

    // 3. DO-WHILE LOOP: Run at least once
    int choice;
    do {
        cout << "\nPress 0 to exit: ";
        cin >> choice;
    } while (choice != 0);

    return 0;
}

Key Keywords: break and continue

• break: Immediately exits the loop entirely.

• continue: Skips the rest of the current loop iteration and jumps straight to the next lap.