🔄 Loops in C: The Magic of Repetition

Imagine you have to write “I love coding” on a paper 100 times. Would you write it manually 100 times? No way! You’d find a smarter way. That’s exactly what loops do in programming!

🎯 The Big Picture

Loops are like a merry-go-round. You get on, go around and around until it’s time to stop. In C programming, loops let your computer repeat tasks without you writing the same code over and over.

Think of it this way:

• Without loops: Write 100 lines to count from 1 to 100
• With loops: Write 3 lines to count from 1 to 100

That’s the power of loops! 🚀

🎠 The Three Merry-Go-Rounds

C gives you three types of loops. Each one is like a different merry-go-round at the park:

1️⃣ The for Loop

🎪 The Story

Imagine you’re at a carnival ticket booth. The sign says: “Rides: Start at ticket 1, stop at ticket 5, use 1 ticket per ride.”

That’s a for loop! You know:

• Where to start (ticket 1)
• When to stop (ticket 5)
• How to move forward (use 1 ticket)

📝 The Recipe

for (start; condition; step) {
    // do something
}

🌟 Simple Example

Print “Hello!” 5 times:

#include <stdio.h>

int main() {
    for (int i = 1; i <= 5; i++) {
        printf("Hello! %d\n", i);
    }
    return 0;
}

Output:

Hello! 1
Hello! 2
Hello! 3
Hello! 4
Hello! 5

🧩 Breaking It Down

graph TD
    A[Start: i = 1] --> B{Is i <= 5?}
    B -->|Yes| C[Print Hello!]
    C --> D[Add 1 to i]
    D --> B
    B -->|No| E[Done! Exit loop]

What happens:

1. i = 1 → We start at 1
2. i <= 5 → Is 1 less than or equal to 5? YES!
3. Print “Hello! 1”
4. i++ → Now i = 2
5. Repeat until i becomes 6 (then we stop)

2️⃣ The while Loop

🎪 The Story

Imagine you’re eating cookies from a jar. You don’t know how many are inside. You just keep eating while there are cookies left!

While (there are cookies) {
    Eat one cookie
}

📝 The Recipe

while (condition) {
    // do something
}

🌟 Simple Example

Count down from 5 to 1:

#include <stdio.h>

int main() {
    int count = 5;

    while (count > 0) {
        printf("%d...\n", count);
        count--;
    }
    printf("Blast off! 🚀\n");
    return 0;
}

Output:

5...
4...
3...
2...
1...
Blast off! 🚀

🧩 Breaking It Down

graph TD
    A[count = 5] --> B{Is count > 0?}
    B -->|Yes| C[Print count]
    C --> D[Subtract 1 from count]
    D --> B
    B -->|No| E[Print Blast off!]

🆚 for vs while

3️⃣ The do-while Loop

🎪 The Story

Imagine a game where you MUST play at least once before deciding to play again.

The game asks: “Play again?” AFTER you finish your first game.

That’s do-while! You do something first, then check if you want to continue.

📝 The Recipe

do {
    // do something
} while (condition);

⚠️ Don’t forget the semicolon at the end!

🌟 Simple Example

Ask for a password (must try at least once):

#include <stdio.h>

int main() {
    int password;

    do {
        printf("Enter password: ");
        scanf("%d", &password);
    } while (password != 1234);

    printf("Access granted!\n");
    return 0;
}

🧩 The Key Difference

graph TD
    subgraph while Loop
    A1[Check condition] --> A2{True?}
    A2 -->|Yes| A3[Do task]
    A3 --> A1
    A2 -->|No| A4[Exit]
    end

    subgraph do-while Loop
    B1[Do task first] --> B2{Continue?}
    B2 -->|Yes| B1
    B2 -->|No| B3[Exit]
    end

4️⃣ Nested Loops

🎪 The Story

Imagine a clock:

• The hour hand moves slowly (outer loop)
• The minute hand goes full circle for EACH hour (inner loop)

That’s a nested loop! A loop inside a loop.

📝 The Recipe

for (outer) {
    for (inner) {
        // inner runs completely
        // for EACH outer run
    }
}

🌟 Simple Example

Print a 3x3 star pattern:

#include <stdio.h>

int main() {
    for (int row = 1; row <= 3; row++) {
        for (int col = 1; col <= 3; col++) {
            printf("* ");
        }
        printf("\n");
    }
    return 0;
}

Output:

* * *
* * *
* * *

🧩 How It Works

graph TD
    A[Row 1 starts] --> B[Print 3 stars]
    B --> C[New line]
    C --> D[Row 2 starts]
    D --> E[Print 3 stars]
    E --> F[New line]
    F --> G[Row 3 starts]
    G --> H[Print 3 stars]
    H --> I[Done!]

Think of it as:

• Outer loop = Rows (vertical)
• Inner loop = Columns (horizontal)

5️⃣ The break Statement

🎪 The Story

You’re on that merry-go-round, spinning happily. Suddenly, you feel sick! 🤢 You shout “STOP! LET ME OFF!”

That’s break! It immediately exits the loop, no matter what.

📝 The Recipe

while (condition) {
    if (emergency) {
        break;  // EXIT NOW!
    }
}

🌟 Simple Example

Find first number divisible by 7:

#include <stdio.h>

int main() {
    for (int i = 1; i <= 100; i++) {
        if (i % 7 == 0) {
            printf("Found: %d\n", i);
            break;  // Stop searching!
        }
    }
    return 0;
}

Output:

Found: 7

Without break, we’d find 7, 14, 21… all of them!

🧩 Visual

graph TD
    A[Start loop] --> B{i = 7?}
    B -->|No| C[Keep searching]
    C --> A
    B -->|Yes| D[BREAK!]
    D --> E[Exit loop immediately]

6️⃣ The continue Statement

🎪 The Story

You’re eating a bowl of grapes. Every time you find a rotten one, you skip it and grab the next grape. You don’t stop eating completely!

That’s continue! It skips THIS round but keeps the loop going.

📝 The Recipe

while (condition) {
    if (skip_this_one) {
        continue;  // Skip to next round
    }
    // This code is skipped when continue runs
}

🌟 Simple Example

Print 1-10 but skip 5:

#include <stdio.h>

int main() {
    for (int i = 1; i <= 10; i++) {
        if (i == 5) {
            continue;  // Skip 5!
        }
        printf("%d ", i);
    }
    return 0;
}

Output:

1 2 3 4 5 6 7 8 9 10

Wait, 5 is there? Let me fix:

1 2 3 4 6 7 8 9 10

See? 5 is missing! We skipped it! 🎉

🆚 break vs continue

graph LR
    subgraph break
    A1[Loop running] --> A2[break hit]
    A2 --> A3[EXIT loop completely]
    end

    subgraph continue
    B1[Loop running] --> B2[continue hit]
    B2 --> B3[Skip to next iteration]
    B3 --> B1
    end

🎯 Quick Reference Table

🚀 You’ve Got This!

Loops are your superpower for making computers do repetitive work. Remember:

1. 🎯 Know your count? → Use for
2. ❓ Don’t know count? → Use while
3. 🎮 Must run once? → Use do-while
4. 🏗️ 2D patterns? → Nest your loops
5. 🛑 Emergency exit? → Use break
6. ⏭️ Skip one? → Use continue

Now go make your computer work hard while you relax! 😎