Evaluation order of assignment operator in GoLang

evaluation-order.md

Evaluation order of assignment operator in GoLang

In GoLang, the evaluation order of assignment operator is straight forward.

The order is:

1. Evaluate the lvalues to Memory Location from left to right.
2. Evaluate the rvalues to constant values from left to right.
3. And finallly, assign rvalues to lvalues from left to right.

The POC:

package main

import (
   "fmt"
)

func main() {
   arr := make([]int, 3)

   arr[echo(0)], arr[echo(1)], arr[echo(2)] = echo(3), arr[echo(0)]+echo(4), echo(5)
   fmt.Println(arr)
}

func echo(v int) int {
   fmt.Println(v)
   return v
}

The ouput:

0
1
2
3
0
4
5
[3 4 5]

Examples

swap.go

package main

import (
   "fmt"
)

func main() {
   a, b := 1, 2
   swap(&a, &b)
   fmt.Println(a, b)
}

func swap(a, b *int) {
   *a, *b = *b, *a
}