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patterngoCritical

Range references instead values

Submitted by: @import:stackoverflow-api··
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valuesrangeinsteadreferences

Problem

I saw that range returns the key and the "copy" of the value. Is there a way for that range to return the address of the item? Example

package main

import "fmt"

type MyType struct {
    field string
}

func main() {
    var array [10]MyType

    for _, e := range array {
        e.field = "foo"
    }

    for _, e := range array {
        fmt.Println(e.field)
        fmt.Println("--")
    }
}


http://play.golang.org/p/AFOGG9NGpx

Here "field" is not modified because range sends the copy of field.
Do I have to use index or is there any other way to modify the value?

Solution

The short & direct answer: no, use the array index instead of the value

So the above code becomes:

package main

import "fmt"

type MyType struct {
    field string
}

func main() {
    var array [10]MyType

    for idx, _ := range array {
        array[idx].field = "foo"
    }

    for _, e := range array {
        fmt.Println(e.field)
        fmt.Println("--")
    }
}

Code Snippets

package main

import "fmt"

type MyType struct {
    field string
}

func main() {
    var array [10]MyType

    for idx, _ := range array {
        array[idx].field = "foo"
    }

    for _, e := range array {
        fmt.Println(e.field)
        fmt.Println("--")
    }
}

Context

Stack Overflow Q#20185511, score: 211

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