位运算及应用
Contents
Go支持的位运算
| 位运算符 | 示例 | 说明 |
|---|---|---|
|（按位或） |
a | b |
对应位有一个是1则返回1，否则返回0 |
&（按位与） |
a & b |
对应位都是1则返回1，否则返回0 |
^（按位异或） |
a ^ b |
对应位不相同则返回1，否则返回0 |
&^（Bit clear） |
a &^ b |
结果假设为a，然后a中为1的位和对应b的位都为1，则将a此位置0 |
<<（左移） |
a << n |
乘以2^n，将a左移n位，高位丢弃，低位补0 |
>>（右移） |
a >> n |
除以2^n，将a右移n位，低位丢弃，但高位不是简单的补0（需要注意符号） |
var tables = []struct {
p1 int
p2 int
symbol string
}{
{4, 5, "|"},
{4, 5, "&"},
{4, 5, "^"},
{6, 11, "&^"},
{4, 2, "<<"},
{4, 1, ">>"},
}
for _, t := range tables {
var result int
switch t.symbol {
case "|":
result = t.p1 | t.p2
case "&":
result = t.p1 & t.p2
case "^":
result = t.p1 ^ t.p2
case "<<":
result = t.p1 << t.p2
case ">>":
result = t.p1 >> t.p2
case "&^":
result = t.p1 &^ t.p2
default:
continue
}
fmt.Printf("%d(%b) %s %d(%b) = %d(%b)\n", t.p1, t.p1, t.symbol, t.p2, t.p2, result, result)
}
// 4(100) | 5(101) = 5(101)
// 4(100) & 5(101) = 4(100)
// 4(100) ^ 5(101) = 1(1)
// 6(110) &^ 11(1011) = 4(100)
// 4(100) << 2(10) = 16(10000)
// 4(100) >> 1(1) = 2(10)
表达包含关系
|表示添加^表示删除- 通过
&判断是否包含
const (
Sunday int = 1 << iota // 1
Monday // 2
Tuesday // 4
Wednesday // 8
Thursday // 16
Friday // 32
Saturday // 64
)
var source = Monday | Wednesday | Friday | Saturday
source = source ^ Wednesday
fmt.Printf("include Sunday: %v\n", source&Sunday == Sunday)
fmt.Printf("include Monday: %v\n", source&Monday == Monday)
fmt.Printf("include Tuesday: %v\n", source&Tuesday == Tuesday)
fmt.Printf("include Wednesday: %v\n", source&Wednesday == Wednesday)
fmt.Printf("include Thursday: %v\n", source&Thursday == Thursday)
fmt.Printf("include Friday: %v\n", source&Friday == Friday)
fmt.Printf("include Saturday: %v\n", source&Saturday == Saturday
// include Sunday: false
// include Monday: true
// include Tuesday: false
// include Wednesday: false
// include Thursday: false
// include Friday: true
// include Saturday: true