我想把字符串赋值给bytes数组:
var arr [20]byte
str := "abc"
for k, v := range []byte(str) {
arr[k] = byte(v)
}
还有别的方法吗?
当前回答
如果有人正在寻找一个快速考虑使用不安全转换片之间，可以参考下面的比较。
package demo_test
import (
"testing"
"unsafe"
)
var testStr = "hello world"
var testBytes = []byte("hello world")
// Avoid copying the data.
func UnsafeStrToBytes(s string) []byte {
return *(*[]byte)(unsafe.Pointer(&s))
}
// Avoid copying the data.
func UnsafeBytesToStr(b []byte) string {
return *(*string)(unsafe.Pointer(&b))
}
func Benchmark_UnsafeStrToBytes(b *testing.B) {
for i := 0; i < b.N; i++ {
_ = UnsafeStrToBytes(testStr)
}
}
func Benchmark_SafeStrToBytes(b *testing.B) {
for i := 0; i < b.N; i++ {
_ = []byte(testStr)
}
}
func Benchmark_UnSafeBytesToStr(b *testing.B) {
for i := 0; i < b.N; i++ {
_ = UnsafeBytesToStr(testBytes)
}
}
func Benchmark_SafeBytesToStr(b *testing.B) {
for i := 0; i < b.N; i++ {
_ = string(testBytes)
}
}
go test -v -bench="^Benchmark" -run=none
输出
cpu: Intel(R) Core(TM) i7-8565U CPU @ 1.80GHz
Benchmark_UnsafeStrToBytes
Benchmark_UnsafeStrToBytes-8 1000000000 0.2465 ns/op
Benchmark_SafeStrToBytes
Benchmark_SafeStrToBytes-8 289119562 4.181 ns/op
Benchmark_UnSafeBytesToStr
Benchmark_UnSafeBytesToStr-8 1000000000 0.2530 ns/op
Benchmark_SafeBytesToStr
Benchmark_SafeBytesToStr-8 342842938 3.623 ns/op
PASS
其他回答
例如,
package main
import "fmt"
func main() {
s := "abc"
var a [20]byte
copy(a[:], s)
fmt.Println("s:", []byte(s), "a:", a)
}
输出:
s: [97 98 99] a: [97 98 99 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]
最终创建了特定于数组的方法来实现这一点。很像每个int类型都有特定方法的编码/二进制包。例如binary.BigEndian。uint16 PutUint16([]字节)。
func byte16PutString(s string) [16]byte {
var a [16]byte
if len(s) > 16 {
copy(a[:], s)
} else {
copy(a[16-len(s):], s)
}
return a
}
var b [16]byte
b = byte16PutString("abc")
fmt.Printf("%v\n", b)
输出:
[0 0 0 0 0 0 0 0 0 0 0 0 0 97 98 99]
请注意，我希望填充在左边，而不是右边。
http://play.golang.org/p/7tNumnJaiN
如果有人正在寻找一个快速考虑使用不安全转换片之间，可以参考下面的比较。
package demo_test
import (
"testing"
"unsafe"
)
var testStr = "hello world"
var testBytes = []byte("hello world")
// Avoid copying the data.
func UnsafeStrToBytes(s string) []byte {
return *(*[]byte)(unsafe.Pointer(&s))
}
// Avoid copying the data.
func UnsafeBytesToStr(b []byte) string {
return *(*string)(unsafe.Pointer(&b))
}
func Benchmark_UnsafeStrToBytes(b *testing.B) {
for i := 0; i < b.N; i++ {
_ = UnsafeStrToBytes(testStr)
}
}
func Benchmark_SafeStrToBytes(b *testing.B) {
for i := 0; i < b.N; i++ {
_ = []byte(testStr)
}
}
func Benchmark_UnSafeBytesToStr(b *testing.B) {
for i := 0; i < b.N; i++ {
_ = UnsafeBytesToStr(testBytes)
}
}
func Benchmark_SafeBytesToStr(b *testing.B) {
for i := 0; i < b.N; i++ {
_ = string(testBytes)
}
}
go test -v -bench="^Benchmark" -run=none
输出
cpu: Intel(R) Core(TM) i7-8565U CPU @ 1.80GHz
Benchmark_UnsafeStrToBytes
Benchmark_UnsafeStrToBytes-8 1000000000 0.2465 ns/op
Benchmark_SafeStrToBytes
Benchmark_SafeStrToBytes-8 289119562 4.181 ns/op
Benchmark_UnSafeBytesToStr
Benchmark_UnSafeBytesToStr-8 1000000000 0.2530 ns/op
Benchmark_SafeBytesToStr
Benchmark_SafeBytesToStr-8 342842938 3.623 ns/op
PASS
我认为这样更好。
package main
import "fmt"
func main() {
str := "abc"
mySlice := []byte(str)
fmt.Printf("%v -> '%s'",mySlice,mySlice )
}
点击这里查看:http://play.golang.org/p/vpnAWHZZk7
安全简单:
[]byte("Here is a string....")
