2.4 Buffer

package main

import (
	"bytes"
	"fmt"
)

func main() {
	strings := []string{"This ", "is ", "even ",
		"more ", "performant "}
	buffer := bytes.Buffer{}
	for _, val := range strings {
		buffer.WriteString(val)
	}

	fmt.Println(buffer.String())
}

/*
This is even more performant 

*/

package main

import (
	"fmt"
)

func main() {

	strings := []string{"This ", "is ", "even ",
		"more ", "performant "}

	bs := make([]byte, 100)
	bl := 0

	for _, val := range strings {
		bl += copy(bs[bl:], []byte(val))
	}

	fmt.Println(string(bs[:]))

}

/*
This is even more performant 

*/

性能测试

package bench

import (
	"bytes"
	"testing"
)

const testString = "test"

func BenchmarkConcat(b *testing.B) {
	var str string
	b.ResetTimer()
	for n := 0; n < b.N; n++ {
		str += testString
	}
	b.StopTimer()
}

func BenchmarkBuffer(b *testing.B) {
	var buffer bytes.Buffer

	b.ResetTimer()
	for n := 0; n < b.N; n++ {
		buffer.WriteString(testString)
	}
	b.StopTimer()
}

func BenchmarkCopy(b *testing.B) {
	bs := make([]byte, b.N)
	bl := 0

	b.ResetTimer()
	for n := 0; n < b.N; n++ {
		bl += copy(bs[bl:], testString)
	}
	b.StopTimer()
}

go test -bench=.
goos: darwin
goarch: amd64
pkg: go_web/bench
BenchmarkConcat-8 500000 114962 ns/op
BenchmarkBuffer-8 100000000 14.8 ns/op
BenchmarkCopy-8 500000000 3.19 ns/op
PASS
ok go_web/bench 61.018s