Loops are an essential part of programming that allow executing a block of code multiple times. In Go, the only loop available is the for loop, but it can be used in different ways to achieve the functionality of while and do-while loops found in other languages.

1. Basic Syntax of for Loop

for initialization; condition; increment {
    // Code to execute
}

🔹 Key Points:
✅ Initialization: Variable is initialized before the loop starts.
✅ Condition: The loop runs as long as the condition is true.
✅ Increment/Decrement: Controls how the loop variable updates.

2. Simple for Loop Example

package main

import "fmt"

func main() {
    for i := 1; i <= 5; i++ {
        fmt.Println("Iteration:", i)
    }
}

🔹 Output:

Iteration: 1
Iteration: 2
Iteration: 3
Iteration: 4
Iteration: 5

👉 Explanation:

• i := 1 → The loop starts with i = 1.
• i <= 5 → The loop runs as long as i is ≤ 5.
• i++ → i is incremented by 1 after each iteration.

3. Using for as a While Loop

In Go, the for loop can also be used like a while loop by omitting the initialization and increment parts.

package main

import "fmt"

func main() {
    i := 1
    for i <= 5 {
        fmt.Println("Value of i:", i)
        i++
    }
}

🔹 Output:

Value of i: 1
Value of i: 2
Value of i: 3
Value of i: 4
Value of i: 5

👉 Explanation:

• No initialization inside for → i is declared before the loop.
• No increment inside for → i++ is manually written inside the loop.

4. Infinite Loop in Go (for without condition)

If a for loop has no condition, it runs forever unless explicitly stopped with break.

package main

import "fmt"

func main() {
    i := 1
    for {
        fmt.Println("Running... Iteration:", i)
        i++
        if i > 5 {
            break
        }
    }
}

🔹 Output:

Running... Iteration: 1
Running... Iteration: 2
Running... Iteration: 3
Running... Iteration: 4
Running... Iteration: 5

👉 Explanation:

• No condition → The loop runs indefinitely.
• if i > 5 { break } → Stops the loop when i > 5.

5. Using break to Exit a Loop

The break statement is used to exit a loop immediately, regardless of the condition.

package main

import "fmt"

func main() {
    for i := 1; i <= 10; i++ {
        if i == 5 {
            fmt.Println("Stopping loop at:", i)
            break
        }
        fmt.Println("Iteration:", i)
    }
}

🔹 Output:

Iteration: 1
Iteration: 2
Iteration: 3
Iteration: 4
Stopping loop at: 5

👉 Explanation:

• When i == 5, the break statement stops the loop.

6. Using continue to Skip an Iteration

The continue statement skips the current iteration and moves to the next one.

package main

import "fmt"

func main() {
    for i := 1; i <= 5; i++ {
        if i == 3 {
            fmt.Println("Skipping iteration:", i)
            continue
        }
        fmt.Println("Iteration:", i)
    }
}

🔹 Output:

Iteration: 1
Iteration: 2
Skipping iteration: 3
Iteration: 4
Iteration: 5

👉 Explanation:

• When i == 3, continue skips the iteration, and the loop moves to i = 4.

7. Nested Loops (Loop Inside Another Loop)

A nested loop is a loop inside another loop.

package main

import "fmt"

func main() {
    for i := 1; i <= 3; i++ {
        for j := 1; j <= 3; j++ {
            fmt.Printf("(%d, %d) ", i, j)
        }
        fmt.Println()
    }
}

🔹 Output:

(1, 1) (1, 2) (1, 3) 
(2, 1) (2, 2) (2, 3) 
(3, 1) (3, 2) (3, 3)

👉 Explanation:

• Outer loop (i) runs 3 times → Controls rows.
• Inner loop (j) runs 3 times per row → Controls columns.

8. Looping Through an Array/Slice Using for range

Go provides the range keyword to iterate over slices, arrays, and maps.

package main

import "fmt"

func main() {
    nums := []int{10, 20, 30, 40, 50}

    for index, value := range nums {
        fmt.Printf("Index: %d, Value: %d\n", index, value)
    }
}

🔹 Output:

Index: 0, Value: 10
Index: 1, Value: 20
Index: 2, Value: 30
Index: 3, Value: 40
Index: 4, Value: 50

👉 Explanation:

• index → Position in the slice.
• value → Value at that position.

🔹 If only values are needed, _ is used to ignore index:

for _, value := range nums {
    fmt.Println(value)
}

Conclusion

🚀 Go only has the for loop, but it is powerful enough to replace while and do-while loops!

Go-তে লুপ কী?

লুপ ব্যবহার করে একটি কোড ব্লক বারবার চালানো যায়, যতক্ষণ না নির্দিষ্ট শর্ত মিথ্যা হয়।

1. সাধারণ for লুপ

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

✅ while লুপের মত ব্যবহার

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

✅ ইনফিনিটি লুপ (for {})

for {
    fmt.Println("চলতে থাকবে...")
}

✅ break এবং continue

for i := 1; i <= 5; i++ {
    if i == 3 {
        continue // 3 বাদ দেবে
    }
    fmt.Println(i)
}