我有这样的一片
v := []string{"this", "is", "a", "sample", "string"}
我想创建ThisIsASampleString。我能想到的唯一方法是首先遍历切片，将它们转换为标题大小写，然后加入它们，即，
x := []string{}
for _, s := range v {
x = append(x, strings.Title(s))
}
strings.Join(x[0:], "")
有没有更好的方法？
【问题讨论】：
标签： string go concatenation
基准测试（go 版本 go1.15.6 linux/amd64）：
BenchmarkBuilder-8 1480506 792 ns/op 112 B/op 8 allocs/op
BenchmarkBuffer-8 1500859 843 ns/op 144 B/op 7 allocs/op
BenchmarkJoin-8 1350139 938 ns/op 160 B/op 7 allocs/op
BenchmarkReplaceAll-8 1513950 793 ns/op 128 B/op 4 allocs/op
BenchmarkLoop-8 2322938 536 ns/op 112 B/op 2 allocs/op
strings.Builder:sb := new(strings.Builder)
for _, s := range v {
sb.WriteString(strings.Title(s))
}
st := sb.String()
bytes.Buffer:p := new(bytes.Buffer)
for _, s := range v {
p.WriteString(strings.Title(s))
}
st = p.String()
strings.Join(x, ""):x := make([]string, len(v))
for i, s := range v {
x[i] = strings.Title(s)
}
st = strings.Join(x, "")
st = strings.ReplaceAll(strings.Title(strings.Join(v, " ")), " ", "")
n := 0
for _, s := range v {
n += len(s)
}
x := make([]rune, 0, n)
for _, s := range v {
for i, r := range s {
if i == 0 {
r = unicode.ToUpper(r)
}
x = append(x, r)
}
}
st = string(x)
代码：
package main
import (
"bytes"
"strings"
"testing"
"unicode"
)
func BenchmarkBuilder(b *testing.B) {
for i := 0; i < b.N; i++ {
sb := new(strings.Builder)
for _, s := range v {
sb.WriteString(strings.Title(s))
}
st = sb.String()
}
}
func BenchmarkBuffer(b *testing.B) {
for i := 0; i < b.N; i++ {
p := new(bytes.Buffer)
for _, s := range v {
p.WriteString(strings.Title(s))
}
st = p.String()
}
}
func BenchmarkJoin(b *testing.B) {
for i := 0; i < b.N; i++ {
x := make([]string, len(v))
for i, s := range v {
x[i] = strings.Title(s)
}
st = strings.Join(x, "")
}
}
func BenchmarkReplaceAll(b *testing.B) {
for i := 0; i < b.N; i++ {
st = strings.ReplaceAll(strings.Title(strings.Join(v, " ")), " ", "")
}
}
func BenchmarkLoop(b *testing.B) {
for i := 0; i < b.N; i++ {
n := 0
for _, s := range v {
n += len(s)
}
x := make([]rune, 0, n)
for _, s := range v {
for i, r := range s {
if i == 0 {
r = unicode.ToUpper(r)
}
x = append(x, r)
}
}
st = string(x)
}
}
var v = []string{"this", "is", "a", "sample", "string"}
var st string
命令：
go test -v -bench=. -count=4 -benchmem -benchtime=1000000x
输出：
goos: linux
goarch: amd64
BenchmarkBuilder-8 1000000 809 ns/op 112 B/op 8 allocs/op
BenchmarkBuilder-8 1000000 812 ns/op 112 B/op 8 allocs/op
BenchmarkBuilder-8 1000000 753 ns/op 112 B/op 8 allocs/op
BenchmarkBuilder-8 1000000 823 ns/op 112 B/op 8 allocs/op
BenchmarkBuffer-8 1000000 845 ns/op 144 B/op 7 allocs/op
BenchmarkBuffer-8 1000000 768 ns/op 144 B/op 7 allocs/op
BenchmarkBuffer-8 1000000 805 ns/op 144 B/op 7 allocs/op
BenchmarkBuffer-8 1000000 811 ns/op 144 B/op 7 allocs/op
BenchmarkJoin-8 1000000 930 ns/op 160 B/op 7 allocs/op
BenchmarkJoin-8 1000000 936 ns/op 160 B/op 7 allocs/op
BenchmarkJoin-8 1000000 896 ns/op 160 B/op 7 allocs/op
BenchmarkJoin-8 1000000 876 ns/op 160 B/op 7 allocs/op
BenchmarkReplaceAll-8 1000000 793 ns/op 128 B/op 4 allocs/op
BenchmarkReplaceAll-8 1000000 759 ns/op 128 B/op 4 allocs/op
BenchmarkReplaceAll-8 1000000 765 ns/op 128 B/op 4 allocs/op
BenchmarkReplaceAll-8 1000000 781 ns/op 128 B/op 4 allocs/op
BenchmarkLoop-8 1000000 535 ns/op 112 B/op 2 allocs/op
BenchmarkLoop-8 1000000 530 ns/op 112 B/op 2 allocs/op
BenchmarkLoop-8 1000000 506 ns/op 112 B/op 2 allocs/op
BenchmarkLoop-8 1000000 487 ns/op 112 B/op 2 allocs/op
PASS
ok 15.250s
【讨论】：
go version。
我会考虑使用 bytes.Buffer 或 strings.Builder 来有效地连接字符串。这是一个使用bytes.Buffer的示例
package main
import (
"testing"
)
var v = []string{"this", "is", "a", "sample", "string"}
func BenchmarkWithBuilder(b *testing.B) {
b.ResetTimer()
for i := 0; i < b.N; i++ {
UsingBuilder(v)
}
}
func BenchmarkWithBuffer(b *testing.B) {
b.ResetTimer()
for i := 0; i < b.N; i++ {
UsingBuffer(v)
}
}
// Since Go 1.10 has strings.Builder.
func UsingBuilder(v []string) string {
var builder strings.Builder
for _, s := range v {
builder.WriteString(strings.Title(s))
}
return builder.String()
}
// pre Go 1.10 the most effective way was to use bytes.Buffer
func UsingBuffer(v []string) string {
var buffer bytes.Buffer
for _, s := range v {
buffer.WriteString(strings.Title(s))
}
return buffer.String()
}
这里是每个函数的基准测试结果。
$ go test -v -bench=. -count=4 -benchmem
goos: linux
goarch: amd64
pkg: test/bench
BenchmarkWithBuilder
BenchmarkWithBuilder-4 1294498 905 ns/op 112 B/op 8 allocs/op
BenchmarkWithBuilder-4 1307007 911 ns/op 112 B/op 8 allocs/op
BenchmarkWithBuilder-4 1313634 911 ns/op 112 B/op 8 allocs/op
BenchmarkWithBuilder-4 1308748 909 ns/op 112 B/op 8 allocs/op
BenchmarkWithBuffer
BenchmarkWithBuffer-4 1388026 869 ns/op 144 B/op 7 allocs/op
BenchmarkWithBuffer-4 1389976 867 ns/op 144 B/op 7 allocs/op
BenchmarkWithBuffer-4 1380103 860 ns/op 144 B/op 7 allocs/op
BenchmarkWithBuffer-4 1380252 874 ns/op 144 B/op 7 allocs/op
PASS
ok test/bench 16.796s
$ go version
go version go1.15.2 linux/amd64
【讨论】：