字符串拼接
字符串拼接有以下几种方法
- 加号+
- fmt.Sprintf
- strings.Join
- bytes.Buffer
- strings.Builder 此方法为官方推荐
新建单元测试文件string_test.go
package test
import (
"bytes"
"fmt"
"strings"
"testing"
)
func BenchmarkFmtSprintf(b *testing.B) {
for i := 0; i < b.N; i++ {
s := fmt.Sprintf("%s%s", "abcdefghijklmnopqrstuvwxyz", "123456789")
fmt.Errorf(s)
}
}
func BenchmarkAdd(b *testing.B) {
for i := 0; i < b.N; i++ {
s := "abcdefghijklmnopqrstuvwxyz" +"123456789"
fmt.Errorf(s)
}
}
func BenchmarkStringsJoin(b *testing.B) {
for i := 0; i < b.N; i++ {
s := strings.Join([]string{"abcdefghijklmnopqrstuvwxyz","123456789"}, "")
fmt.Errorf(s)
}
}
func BenchmarkBuffer(b *testing.B) {
for i := 0; i < b.N; i++ {
buf := bytes.Buffer{}
buf.WriteString("abcdefghijklmnopqrstuvwxyz")
buf.WriteString("123456789")
fmt.Errorf(buf.String())
}
}
func BenchmarkBuilder(b *testing.B) {
for i := 0; i < b.N; i++ {
builder := strings.Builder{}
builder.WriteString("abcdefghijklmnopqrstuvwxyz")
builder.WriteString("123456789")
fmt.Errorf(builder.String())
}
}执行
go test string_test.go -benchmem -bench=".*"
结果：
BenchmarkFmtSprintf-4 2962962 400.6 ns/op 112 B/op 3 allocs/op
BenchmarkAdd-4 6629833 207.7 ns/op 64 B/op 2 allocs/op
BenchmarkStringsJoin-4 4255318 291.6 ns/op 112 B/op 3 allocs/op
BenchmarkBuffer-4 2948402 368.3 ns/op 176 B/op 4 allocs/op
BenchmarkBuilder-4 3149605 352.1 ns/op 160 B/op 4 allocs/op
PASS
ok command-line-arguments 8.219s
执行效率排序+>join>fmt.Sprintf>strings.Builder>bytes.Buffer
新建单元测试文件string2_test.go
package test
import (
"bytes"
"fmt"
"strings"
"testing"
)
func BenchmarkAdd2(b *testing.B) {
s:= "abcdefghijklmnopqrstuvwxyz"
for i := 0; i < b.N; i++ {
s += "abcdefghijklmnopqrstuvwxyz"
}
fmt.Errorf(s)
}
func BenchmarkBuffer2(b *testing.B) {
buf := bytes.Buffer{}
for i := 0; i < b.N; i++ {
buf.WriteString("abcdefghijklmnopqrstuvwxyz")
}
fmt.Errorf(buf.String())
}
func BenchmarkBuilder2(b *testing.B) {
builder := strings.Builder{}
for i := 0; i < b.N; i++ {
builder.WriteString("abcdefghijklmnopqrstuvwxyz")
}
fmt.Errorf(builder.String())
}执行
go test string2_test.go -benchmem -bench=".*"
结果：
goos: windows
goarch: amd64
cpu: Intel(R) Core(TM) i7-6500U CPU @ 2.50GHz
BenchmarkAdd2-4 10000 101400 ns/op 133806 B/op 1 allocs/op
BenchmarkBuffer2-4 15974260 79.25 ns/op 145 B/op 0 allocs/op
BenchmarkBuilder2-4 17142856 59.38 ns/op 189 B/op 0 allocs/op
PASS
ok command-line-arguments 4.912s
执行效率排序：strings.Builder>bytes.Buffer>加号
且strings.Builder和bytes.Buffer分配内存大小和次数，要比加号效率更好
总结
由此可知在不同的使用场景，应使用不同的拼接方法，在一些简单的拼接字符串里使用加号简单高效，在复杂的拼接场景推荐strings.Builder和bytes.Buffer。
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