Which of the following are valid keywords in Go for controlling a loop?

Question

I saw this question that for correct answer had 'for and range'.

But the for statement is the only available looping statement in Go,and the range keyword allows you to iterate over items of a list like an array or a map. For understanding it, you could translate the range keyword to for each index of.

//for loop
package main

import "fmt"

func main() {
for i := 0; i < 5; i++ {
    fmt.Println("Value of i is now:", i)
    }
}

 //range is used inside a for loop


a := [...]string{"a", "b", "c", "d"}
for i := range a {
    fmt.Println("Array item", i, "is", a[i])
}
capitals := map[string] string {"France":"Paris", "Italy":"Rome",     "Japan":"Tokyo" }
for key := range capitals {
    fmt.Println("Map item: Capital of", key, "is", capitals[key])
    }

//range can also return two items, the index/key and the corresponding value 
for key2, val := range capitals {
    fmt.Println("Map item: Capital of", key2, "is", val)
    }

I don't understand the question? The range keyword can be used in conjunction with a for loop. More info [here](https://github.com/golang/go/wiki/Range) — william.taylor.09, May 27 '16 at 12:53
What exactly is your question? The syntax is spelled out in the spec: https://golang.org/ref/spec#For_statements — JimB, May 27 '16 at 12:54
The question was:Which of the following are valid keywords in Go for controlling a loop? the correct answers were for and range.And I know and searched again to make sure that the for statement is the only available looping statement in Go — Jetlum Ajeti, May 27 '16 at 13:00
Both of them are valid. The only loop function missing in go is the `while` or `do..while`. — Endre Simo, May 27 '16 at 13:02
if this is for graded coursework I think `for` alone should be an acceptable answer, since you cant use range without for — Plato, May 27 '16 at 13:10
Yes,this was my thought too,since you can't use range without for. — Jetlum Ajeti, May 27 '16 at 13:11

score 0 · Accepted Answer · edited Sep 27 '17 at 18:07

I think the question is about Different Forms of For Loop:
simple loop variants working sample:

package main

import "fmt"

func main() {
    //0 1 2 3 4 5 6 7 8 9
    for i := 0; i < 10; i++ {
        fmt.Print(i, " ")
    }
    fmt.Println()

    i := 0
    for ; i < 10; i++ {
        fmt.Print(i, " ")
    }
    fmt.Println()

    for i := 0; i < 10; {
        fmt.Print(i, " ")
        i++
    }
    fmt.Println()

    //2 4 6 8 10 12 14 16 18 20
    for i := 1; ; i++ {
        if i&1 == 1 {
            continue
        }
        if i == 22 {
            break
        }
        fmt.Print(i, " ")
    }
    fmt.Println()

    i = 0
    for {
        fmt.Print(i, " ")
        i++
        if i == 10 {
            break
        }

    }
    fmt.Println()

    for i, j := 0, 0; i < 5 && j < 10; i, j = i+1, j+2 {
        fmt.Println(i, j)
    }
}

for array, slice,string, map, channel using range keyword:

package main

import "fmt"

func main() {
    ary := [5]int{0, 1, 2, 3, 4}
    for index, value := range ary {
        fmt.Print("ary[", index, "] =", value, " ")
    }
    fmt.Println()
    for index := range ary {
        fmt.Print("ary[", index, "] =", ary[index], " ")
    }
    fmt.Println()
    for _, value := range ary {
        fmt.Print(value, " ")
    }
    fmt.Println()

    slice := []int{20, 21, 22, 23, 24, 25, 26, 27, 28, 29}
    for index, value := range slice {
        fmt.Println("slice[", index, "] =", value)
    }
    fmt.Println()

    str := "Hello"
    for index, value := range str {
        fmt.Println("str[", index, "] =", value)
    }
    fmt.Println()

    mp := map[string]int{"One": 1, "Two": 2, "Three": 3}
    for key, value := range mp {
        fmt.Println("map[", key, "] =", value)
    }
    fmt.Println()

    ch := make(chan int, 10)
    for i := 0; i < 10; i++ {
        ch <- i
    }
    close(ch)

    for i := range ch {
        fmt.Print(i, " ")
    }
    fmt.Println()
}

and Label for break Label and continue Label:

package main

import "fmt"

func main() {
    a, b := 1, 1
Loop1:
    for {
        b++
    Loop2:
        for {
            a++
            switch {
            case a == 2:
                fallthrough
            case a == 3:
                fmt.Println(3)
            case a == 4, a == 5:
                continue
            case a == 7:
                continue Loop1
            case a == 9:
                break Loop2
            case a == 10:
                break Loop1
            case a == 8:
                break
            default:
                fmt.Println(a, b)
            }
        }
    }
}

Which of the following are valid keywords in Go for controlling a loop?

1 Answers1