Golang: loop

Go has only one loop construct, the for loop.

package main

import "fmt"

// example of for loop

func main() {
        // scope of i is within the curly bracket {}
        for i := 0; i < 4; i++ {
                fmt.Println(i)
        }
}

// 0
// 1
// 2
// 3

Note: no parenthesis after the for keyword. Adding parenthesis creates invalid syntax.

Curly brackets {} are always required.

Like While Loop

• The variable init part is optional.
• The variable increment part (called the post statement) is optional.

package main

import "fmt"

// for loop with just test condition

func main() {
        var ss = 1
        for ss <= 3 {
                fmt.Println(ss)
                ss++
        }
}

// prints
// 1
// 2
// 3

This is the same as C language's “while” statement.

Infinite Loop

package main

import "fmt"

func main() {

        uu := 1

        // infinite loop, use break to exit
        for {
                uu++
                fmt.Println(uu)
                if uu >= 4 {
                        break
                }
        }
}

break loop

package main

import "fmt"

func main() {

        for i := 0; i < 9; i++ {
                if i == 4 {
                        break
                }
                fmt.Println(i)
        }

}

continue loop

package main

import "fmt"

func main() {
        for i := 1; i <= 3; i++ {
                for j := 1; j <= 99; j++ {
                        if j <= 2 {
                                fmt.Println(i, j)
                        } else {
                                continue
                        }
                }
        }
}

// 1 1
// 1 2
// 2 1
// 2 2
// 3 1
// 3 2

Reference

The Go Programming Language Specification - The Go Programming Language#For_statements

The Go Programming Language Specification - The Go Programming Language#Break_statements

The Go Programming Language Specification - The Go Programming Language#Continue_statements