for-loop

#include <iostream>
#include <string>
using namespace std;

int main() {

    // ===================================================
    // 1. BASIC FOR LOOP
    // ===================================================
    // Syntax: for (statement 1; statement 2; statement 3)
    // Statement 1: Executed once before loop starts (init)
    // Statement 2: Condition for executing the loop
    // Statement 3: Executed every time after the loop block runs
    cout << "=== 1. BASIC FOR LOOP (0 TO 4) ===" << endl;

    for (int i = 0; i < 5; i++) {
        cout << i << "\n";
    }


    // ===================================================
    // 2. COUNTDOWN & STEP INCREMENTS
    // ===================================================
    cout << "\n=== 2. COUNTDOWN (5 TO 1) ===" << endl;

    for (int i = 5; i > 0; i--) {
        cout << i << "\n";
    }

    cout << "\n=== STEP BY 10 (0 TO 100) ===" << endl;

    for (int i = 0; i <= 100; i += 10) {
        cout << i << "\n";
    }

    cout << "\n=== EVEN NUMBERS (0 TO 10) ===" << endl;

    for (int i = 0; i <= 10; i = i + 2) {
        cout << i << "\n";
    }

    cout << "\n=== ODD NUMBERS (1 TO 10) ===" << endl;

    for (int i = 1; i <= 10; i = i + 2) {
        cout << i << "\n";
    }

    cout << "\n=== POWERS OF 2 (UP TO 512) ===" << endl;

    for (int i = 2; i <= 512; i *= 2) {
        cout << i << "\n";
    }


    // ===================================================
    // 3. SUM OF NUMBERS & MULTIPLICATION TABLE
    // ===================================================
    cout << "\n=== 3. SUM OF NUMBERS (1 TO 5) ===" << endl;

    int sum = 0;
    for (int i = 1; i <= 5; i++) {
        sum = sum + i;
    }
    cout << "Sum is " << sum << endl;

    cout << "\n=== MULTIPLICATION TABLE FOR 2 ===" << endl;

    int number = 2;
    for (int i = 1; i <= 10; i++) {
        cout << number << " x " << i << " = " << number * i << "\n";
    }


    // ===================================================
    // 4. NESTED LOOPS
    // ===================================================
    // Loop inside another loop (inner loop runs for each outer iteration)
    cout << "\n=== 4. NESTED LOOPS ===" << endl;

    for (int i = 1; i <= 2; ++i) {
        cout << "Outer: " << i << "\n"; // Executes 2 times
        for (int j = 1; j <= 3; ++j) {
            cout << " Inner: " << j << "\n"; // Executes 6 times (2 * 3)
        }
    }

    cout << "\n=== MULTIPLICATION TABLE GRID (1 TO 3) ===" << endl;

    for (int i = 1; i <= 3; i++) {
        for (int j = 1; j <= 3; j++) {
            cout << i * j << " ";
        }
        cout << "\n";
    }


    // ===================================================
    // 5. THE FOR-EACH LOOP (C++11 RANGE-BASED)
    // ===================================================
    // Syntax: for (type variableName : arrayName)
    cout << "\n=== 5. FOR-EACH LOOP WITH ARRAY ===" << endl;

    int myNumbers[5] = {10, 20, 30, 40, 50};
    for (int num : myNumbers) {
        cout << num << "\n";
    }

    cout << "\n=== FOR-EACH LOOP WITH STRING ===" << endl;

    string word = "Hello";
    for (char c : word) {
        cout << c << "\n";
    }

    return 0;
}