C++ Loops (for, while) Tutorial

1. for Loop

The for loop is ideal for running a block of code a specific number of times:

#include <iostream>
using namespace std;

int main() {
    for (int i = 0; i < 5; i++) {
        cout << "Iteration " << i + 1 << endl;
    }
    return 0;
}
                

In this example, the loop runs 5 times, incrementing i with each iteration.

2. while Loop

The while loop continues as long as its condition is true:

#include <iostream>
using namespace std;

int main() {
    int count = 0;

    while (count < 5) {
        cout << "Count is " << count << endl;
        count++;
    }
    return 0;
}
                

This loop increments count until it reaches 5.

3. do-while Loop

The do-while loop guarantees at least one execution of the code block:

#include <iostream>
using namespace std;

int main() {
    int num = 10;

    do {
        cout << "Number is " << num << endl;
        num--;
    } while (num > 0);

    return 0;
}
                

In this example, the loop prints and decrements num until it becomes zero.

4. Nested Loops

Loops can be nested to handle multi-dimensional data or repeated patterns:

#include <iostream>
using namespace std;

int main() {
    for (int i = 1; i <= 3; i++) {
        for (int j = 1; j <= 3; j++) {
            cout << "(" << i << ", " << j << ") ";
        }
        cout << endl;
    }
    return 0;
}
                

This example demonstrates nested loops to print a 3x3 grid.

5. Infinite Loops

An infinite loop runs indefinitely and should be avoided unless intentionally used:

while (true) {
    cout << "This will run forever unless interrupted!" << endl;
}
                

Use break or conditions to exit loops safely.

6. Best Practices

• Prefer for loops for known iteration counts.
• Use while or do-while loops for uncertain iterations.
• Always ensure a loop has an exit condition to avoid infinite loops.