swap of two variable

package main
import "fmt"
func main () {
    a := 1
    b := 2
    a = a + b
    b = a - b 
    a = a - b
    fmt.Println(a,b)
    c := 1
    d := 2
    c = c^d
    d = c^d
    c = c^d
    fmt.Println(c,d)
}

2 1
2 1

异或：相同为0不相同为1

Example：
1:
10101
^ 00000
——————-
10101
a^0=a

2:

10101
^ 11100
——————-
01001

01001
^ 11100
——————-
10101