fmt.Fprint vs bytes.WriteString

writestring_test.go

package writestring

import (
	"bytes"
	"fmt"
	"math/rand"
	"testing"
)

// go test -bench=. -benchtime 20s
//
// Benchmark_Fmt		100000000	       405 ns/op
// Benchmark_WriteString	500000000	       133 ns/op

var letters = []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")

func randSeq(n int) string {
	b := make([]rune, n)
	for i := range b {
		b[i] = letters[rand.Intn(len(letters))]
	}
	return string(b)
}

func Benchmark_Fmt(b *testing.B) {
	var str = randSeq(rand.Intn(50))
	var buf *bytes.Buffer = bytes.NewBuffer(nil)
	for i := 0; i < b.N; i++ {
		buf = bytes.NewBuffer(nil)
		fmt.Fprint(buf, str)
	}
}

func Benchmark_WriteString(b *testing.B) {
	var str = randSeq(rand.Intn(50))
	var buf *bytes.Buffer = bytes.NewBuffer(nil)
	for i := 0; i < b.N; i++ {
		buf = bytes.NewBuffer(nil)
		buf.WriteString(str)
	}
}