Go – For Loop Examples

In this tutorial, we will explore the examples for For Loop in the Go programming language (Golang). The for loop is a control structure that allows code to be executed repeatedly based on a condition. Go simplifies looping with a single for construct, making it powerful and versatile. We will cover basic syntax, variations of the for loop, and practical examples.

Syntax of For Loop

The basic syntax of a for loop in Go is:

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

Here:

  • Initialization: Initializes the loop variable (executed once).
  • Condition: The loop runs while this condition evaluates to true.
  • Post: Updates the loop variable after each iteration.

Example of a Basic For Loop

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package main

import "fmt"

func main() {
    // Basic for loop to print numbers from 1 to 5
    for i := 1; i <= 5; i++ {
        fmt.Println(i)
    }
}

Variations of For Loop

1. Infinite Loop

A for loop without initialization, condition, or post becomes an infinite loop:

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package main

import "fmt"

func main() {
    count := 0
    for {
        fmt.Println("Infinite loop")
        count++
        if count == 3 {
            break // Exit the loop after 3 iterations
        }
    }
}

If there is no break statement, then the loop would have run indefinitely.

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package main

import "fmt"

func main() {
    count := 0
    for {
        fmt.Println("Infinite loop")
        count++
    }
}

2. While-Like Loop

A for loop can mimic a while loop by omitting initialization and post statements:

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package main

import "fmt"

func main() {
    count := 1
    for count <= 5 {
        fmt.Println(count)
        count++
    }
}

3. Loop Over Arrays or Slices

You can use a for loop to iterate over arrays or slices:

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package main

import "fmt"

func main() {
    nums := []int{10, 20, 30, 40, 50}
    for i := 0; i < len(nums); i++ {
        fmt.Println("Index:", i, "Value:", nums[i])
    }
}

4. Range Loop

The range keyword simplifies iterating over arrays, slices, maps, and strings:

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package main

import "fmt"

func main() {
    nums := []int{10, 20, 30, 40, 50}
    for index, value := range nums {
        fmt.Println("Index:", index, "Value:", value)
    }
}

5. Nested Loops

A for loop can be nested within another for loop:

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package main

import "fmt"

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

Break and Continue in For Loops

The break statement exits the loop prematurely, while the continue statement skips the current iteration and moves to the next:

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package main

import "fmt"

func main() {
    for i := 1; i <= 5; i++ {
        if i == 3 {
            continue // Skip iteration for i == 3
        }
        if i == 5 {
            break // Exit the loop when i == 5
        }
        fmt.Println(i)
    }
}

Conclusion

The for loop in Go is versatile and powerful, allowing for various loop constructs such as infinite loops, while-like loops, and range-based iterations.