交换功能在Golang中不起作用

Question

Actually i just start to learn golang . In the beginning i think that = and := are same . But then i understand that there is some difference between this two .

I learned swap function in golnag

import "fmt"

func swap(x, y string) (string, string) {
    return y, x
}

func main() {
    a, b := swap("hello", "world")
    fmt.Println(a, b)
}

But when i rewrite this function using var this is not working

package main

import "fmt"

func swap(x, y string) (string, string) {
    return y, x
}

func main() {
   var a, b string
    a ="hello"
    b="world"
     swap(a, b)
    fmt.Println(a, b)
}

what is the error in this program ?

Answer 1

The reason is that in second case values returned from swap are ignored. SO nothing is changed.

Try: https://play.golang.org/p/uADEf5X15g

package main

import "fmt"

func swap(x, y string) (string, string) {
    return y, x
}

func main() {
    var a, b string
    a = "hello"
    b = "world"
    a, b = swap(a, b)  ////   <----
    fmt.Println(a, b)
}