🔁 Go For Loop – Iterate Efficiently with Range, Conditions & Infinite Loops (2025 Guide)

🧲 Introduction – What Is a for Loop in Go?

Go’s for loop is the only looping construct in the language, but it’s incredibly versatile. With it, you can perform traditional counted loops, condition-based loops, infinite loops, and even iterate over collections using range.

🎯 In this section, you’ll learn:

• All valid forms of for loops in Go
• How to loop through arrays, slices, maps, and strings using range
• How to break, continue, and control flow inside loops
• Best practices and real-world examples

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✅ Basic Syntax – Traditional For Loop

for init; condition; post {
    // block of code
}

Example:

for i := 1; i <= 5; i++ {
    fmt.Println(i)
}

📤 Output:

1
2
3
4
5

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🔄 While-Style For Loop

Go does not have a while keyword, but the for loop can act like one:

i := 0
for i < 3 {
    fmt.Println(i)
    i++
}

📤 Output:

0
1
2

✅ This behaves exactly like a traditional while loop.

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♾️ Infinite Loop

for {
    fmt.Println("Running forever...")
}

❗ Be cautious—use a break to exit when needed.

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🔁 Loop with range – Iterate Collections

Use range to iterate over arrays, slices, maps, strings, and channels.

✅ Array/Slice:

nums := []int{10, 20, 30}
for i, v := range nums {
    fmt.Printf("Index %d = %d\n", i, v)
}

📤 Output:

Index 0 = 10  
Index 1 = 20  
Index 2 = 30

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✅ Map:

m := map[string]int{"a": 1, "b": 2}
for key, val := range m {
    fmt.Printf("%s → %d\n", key, val)
}

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✅ String (Unicode-safe):

for i, ch := range "Go💡" {
    fmt.Printf("%d: %c\n", i, ch)
}

✅ range on strings handles Unicode characters correctly.

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🧼 Break, Continue, and Label

🔚 Break:

for i := 0; i < 10; i++ {
    if i == 5 {
        break
    }
    fmt.Println(i)
}

📤 Stops the loop when i == 5.

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🔁 Continue:

for i := 1; i <= 5; i++ {
    if i%2 == 0 {
        continue
    }
    fmt.Println(i)
}

📤 Skips even numbers.

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🏷️ Labeled Break (for nested loops):

Outer:
for i := 1; i <= 3; i++ {
    for j := 1; j <= 3; j++ {
        if i*j > 4 {
            break Outer
        }
        fmt.Println(i, j)
    }
}

📤 Exits both loops when condition matches.

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🧠 Best Practices

Practice	Why?
Prefer range for collections	More readable and idiomatic
Use labels sparingly	Only for breaking nested loops
Avoid infinite loops unless needed	They can hang processes without control

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📌 Summary – Recap & Next Steps

Go’s for loop is simple yet powerful. Whether you need a basic counter, a while-style condition, or to iterate over collections, the for construct handles it all efficiently and elegantly.

🔍 Key Takeaways:

• for is the only loop in Go but supports multiple forms
• Use range for idiomatic iteration over slices, maps, strings, etc.
• Use break, continue, and labels to control loop behavior
• Infinite loops require manual exit conditions

⚙️ Next: Learn about Go Functions to modularize and reuse logic efficiently.

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❓ FAQs – Go For Loop

❓ Is there a while loop in Go?
✅ No. Use for with only a condition: for condition {}

❓ Can I iterate over a string with range?
✅ Yes. It handles Unicode characters properly.

❓ What does range return in a map?
✅ It returns key, value pairs for each map entry.

❓ How can I skip the current iteration?
✅ Use continue to skip to the next loop cycle.

❓ Can I break out of nested loops?
✅ Yes. Use labeled break to exit outer loops.

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