Kotlin Loops: The Magic of Repetition 🔄🚀

Imagine you're a robot 🤖 assigned to wash 10 dishes 🍽️. Would you manually wash each dish one by one, or would you automate the process?

Loops in Kotlin help us automate repetitive tasks so that we don’t have to write the same code again and again.

📌 In this blog, we’ll cover:

✅ What are loops? 🤔
✅ Types of loops in Kotlin (for, while, do-while) 🔁
✅ Features, examples, and best use cases ✨

Let’s dive into loops! 🏊‍♂️

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1️⃣ What Are Loops? 🔄

A loop is a control structure that repeats a block of code until a condition is met.

📌 Think of it like this:

• "Keep running until you reach the finish line." 🏃‍♂️🏁
• "Keep watering the plant until the soil is moist." 🌱💦

Loops help in:
🔹 Reducing redundancy (no need to copy-paste code).
🔹 Automating tasks (like processing lists, arrays, etc.).
🔹 Making the code clean and efficient.

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2️⃣ Types of Loops in Kotlin 🏗️

Kotlin provides three types of loops:

Loop Type	When to Use?
for loop	When iterating over a range, list, or array.
while loop	When we don’t know how many times the loop should run.
do-while loop	When we want to execute at least once, then check the condition.

Let’s explore each of them in detail! 🕵️‍♂️

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3️⃣ for Loop: The Repeater 🔁

The for loop is used when we need to iterate over a range, list, or array.

🔹 Syntax of for loop

for (item in collection) {
    // Execute this block
}

🔹 Example: Counting from 1 to 5

for (i in 1..5) {
    println("Number: $i")
}

📌 Output:

Number: 1  
Number: 2  
Number: 3  
Number: 4  
Number: 5  

🧐 Explanation:

• 1..5 is a range (numbers from 1 to 5).
• The loop runs 5 times, printing each number.

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4️⃣ for with step & downTo 🚀

🔹 Example: Skipping Numbers with step

for (i in 1..10 step 2) {
    println(i)
}

📌 Output: 1 3 5 7 9

🔹 Example: Counting Backward with downTo

for (i in 10 downTo 1) {
    println(i)
}

📌 Output: 10 9 8 7 6 5 4 3 2 1

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5️⃣ while Loop: The Condition Checker 🔄

A while loop repeats as long as a condition is true.

🔹 Syntax of while loop

while (condition) {
    // Execute this block
}

🔹 Example: Counting Down to Launch 🚀

var countdown = 5

while (countdown > 0) {
    println("Launching in $countdown...")
    countdown--  // Decrease countdown
}

println("🚀 Blast Off!")

📌 Output:

Launching in 5...  
Launching in 4...  
Launching in 3...  
Launching in 2...  
Launching in 1...  
🚀 Blast Off!  

🧐 Explanation:

• The loop runs until countdown reaches 0.
• countdown-- decreases the value in each iteration.

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6️⃣ do-while Loop: The Must-Run Loop ✅

Unlike while, the do-while loop always runs at least once (because the condition is checked after execution).

🔹 Syntax of do-while loop

do {
    // Execute this block
} while (condition)

🔹 Example: Asking for Password 🔑

var password: String

do {
    print("Enter password: ")
    password = readLine()!!
} while (password != "kotlin123")

println("✅ Access Granted!")

📌 How It Works?

• The loop always asks for a password at least once.
• If the user enters the wrong password, it repeats.
• If they enter "kotlin123", it exits the loop.

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7️⃣ Breaking & Skipping Loops 🚀

🔹 break: Stops the Loop Immediately 🚫

for (i in 1..10) {
    if (i == 5) break  // Stops loop when i is 5
    println(i)
}

📌 Output: 1 2 3 4

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🔹 continue: Skips Current Iteration 🔄

for (i in 1..5) {
    if (i == 3) continue  // Skips 3
    println(i)
}

📌 Output: 1 2 4 5 (Skips 3)

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8️⃣ Infinite Loops: BE CAREFUL! ⚠️

If a loop never meets the exit condition, it becomes infinite!

❌ Example: Infinite while Loop

var x = 5

while (x > 0) {
    println("Looping forever...")  // Oops! No x--
}

🔴 Solution: Always update the loop variable (x-- in this case).

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9️⃣ for vs while vs do-while: When to Use What? 🤔

Feature	for Loop	while Loop	do-while Loop
Use Case	Known number of repetitions	Unknown repetitions	Must execute at least once
Condition Checking	Before loop starts	Before each iteration	After first execution
Example	Iterating over lists, ranges	Waiting for user input	Login system (password check)

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🔟 Conclusion: Loops Make Life Easier! 🚀

🔹 Use for for ranges, lists, and arrays.
🔹 Use while when the number of repetitions is unknown.
🔹 Use do-while when you need to run at least once.
🔹 Use break and continue to control loops efficiently.

Now, go ahead and experiment with Kotlin loops in your own projects! 🎯

💬 Which loop do you use the most? Let me know in the comments! ⬇️😊