golang 运算符

1. golang 运算符

1.1. Types of Operators

1. Bitwise Operators (位运算符)
2. Logical Operators (逻辑运算符)
3. Arithmetic Operators (算术运算符)
4. Assignment Operators (赋值运算符)
5. Comparison Operators (比较运算符)

1.2. Bitwise Operators (位运算符)

package main

import "fmt"

func main() {
    x := 3
    y := 5
	z := false
    // 3 -> 011
    // 5 -> 101
    fmt.Println("X AND Y = ", x & y)
    fmt.Println("X OR Y = ", x | y)
    fmt.Println("X EXOR Y = ", x ^ y)
    fmt.Println("X Right Shift 1  = ", x >> 1)
    fmt.Println("X Right Shift 2  = ", x >> 2)
    fmt.Println("Y Left Shift 1 = ", y << 1)
}

$ go run bitwise/main.go

X AND Y =  1
X OR Y =  7
X EXOR Y =  6
X Right Shift 1  =  1
X Right Shift 2  =  0
Y Left Shift 1 =  10

很多编程语言使用 ~ 作为一元按位取反(NOT)操作符, Go 重用 ^ XOR 操作符来按位取反:

// 错误的取反操作
func main() {
    fmt.Println(~2) // bitwise complement operator is ^
}
 
// 正确示例
func main() {
    var d uint8 = 2
    fmt.Printf("%08b\n", d)     // 00000010
    fmt.Printf("%08b\n", ^d)    // 11111101
}

同时 ^ 也是按位异或（XOR）操作符:

10000010 ^ 00000010 = 10000000

1.3. Logical Operators (逻辑运算符)

package main

import "fmt"

func main() {
    a := 45
    b := "Something"
    fmt.Println(a > 40 && b == "Something")
    fmt.Println(a < 40 && b == "Something")
    fmt.Println(a < 40 || b == "Something")
    fmt.Println(a < 40 || b != "Something")
    fmt.Println(!(a < 40 || b != "Something"))
}

$ go run logical/main.go

true
false
true
false
true

1.4. Arithmetic Operators (算术运算符)

package main

import "fmt"

func main() {
    a := 30
    b := 50
    fmt.Println("A + B = ", a+b)
    fmt.Println("A - B = ", a-b)
    fmt.Println("A * B = ", a*b)
    fmt.Println("A / B = ", a/b)
    fmt.Println("A % B = ", a%b)
}

$ go run arithmetic/main.go
A + B =  80
A - B =  -20
A * B =  1500
A / B =  0
A % B =  30

package main

import "fmt"

func main() {
    k := 3
    j := 20
    fmt.Println("k = ", k)
    fmt.Println("j = ", j)
    k++
    j--
    fmt.Println("k = ", k)
    fmt.Println("j = ", j)
}

$ go run arithmetic/main.go

k =  3
j =  20

k =  4
j =  19

1.5. Assignment Operators (赋值运算符)

package main

import "fmt"

func main() {
    var a int = 100
    b := 20
    fmt.Println("a = ", a)
    fmt.Println("b = ", b)
    a += 30
    fmt.Println("a = ", a)
    b -= 5
    fmt.Println("b = ", b)
    a *= b
    fmt.Println("a = ", a)
    fmt.Println("b = ", b)
    a /= b
    fmt.Println("a = ", a)
    fmt.Println("b = ", b)
    a %= b
    fmt.Println("a = ", a)
    fmt.Println("b = ", b)
}

$ go run assignment/main.go

a =  100
b =  20

a =  130
b =  15

a =  1950
b =  15

a =  130
b =  15

a =  10
b =  15

1.6. Comparison Operators (比较运算符)

package main

import "fmt"

func main() {
    a := 45
    b := 12
    fmt.Println("Is A equal to B ? ", a == b)
    fmt.Println("Is A not equal to B ? ", a != b)
    fmt.Println("Is A greater than B ? ", a > b)
    fmt.Println("Is A less than B ? ", a < b)
    fmt.Println("Is A greater than or equal to B ? ", a >= b)
    fmt.Println("Is A less than or equal to B ? ", a <= b)
}

$ go run comparison/main.go

Is A equal to B ?  false
Is A not equal to B ?  true
Is A greater than B ?  true
Is A less than B ?  false
Is A greater than or equal to B ?  true
Is A less than or equal to B ?  false