cp string

copy_string.go

package main_test

import (
	"testing"
	"fmt"
)

var longStr = "121212123123231231231231311111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111123123"
var shortStr = "1212121231232312312311"

func BenchmarkLC1(b *testing.B) {
	for i := 0; i < b.N; i++ {
		longStr = copy1(longStr)
	}
}

func BenchmarkLC2(b *testing.B) {
	for i := 0; i < b.N; i++ {
		longStr = copy2(longStr)
	}
}

func BenchmarkLC3(b *testing.B) {
	for i := 0; i < b.N; i++ {
		longStr = copy3(longStr)
	}
}

func BenchmarkLC4(b *testing.B) {
	for i := 0; i < b.N; i++ {
		longStr = copy4(longStr)
	}
}

func BenchmarkSC1(b *testing.B) {
	for i := 0; i < b.N; i++ {
		longStr = copy1(shortStr)
	}
}

func BenchmarkSC2(b *testing.B) {
	for i := 0; i < b.N; i++ {
		longStr = copy2(shortStr)
	}
}

func BenchmarkSC3(b *testing.B) {
	for i := 0; i < b.N; i++ {
		longStr = copy3(shortStr)
	}
}

func BenchmarkSC4(b *testing.B) {
	for i := 0; i < b.N; i++ {
		longStr = copy4(shortStr)
	}
}

func copy1(s string) string {
	return fmt.Sprintf("%s", s)
}

func copy2(s string) string {
	return string([]byte(s))
}

func copy3(a string) string {
	return (a + " ")[:len(a)]
}

func copy4(a string) string {
	if len(a) == 0 {
		return ""
	}
	return a[0:1] + a[1:]
}

func BenchmarkCopyString2(b *testing.B) {
	a := "123"
	for i := 0; i < b.N; i++ {
		a = (a + "")[:len(a)]
	}
}

func BenchmarkCopyString3(b *testing.B) {
	a := "123"
	for i := 0; i < b.N; i++{
		a = string(hack.Slice(a))
	}
}

func BenchmarkCopyString4(b *testing.B) {
	a := "123"
	for i:= 0; i< b.N; i ++{
		a = string([]byte(a))
	}
}

BenchmarkCopyString2-4 100000000 15.9 ns/op 0 B/op 0 allocs/op
BenchmarkCopyString3-4 50000000 42.6 ns/op 3 B/op 1 allocs/op
BenchmarkCopyString4-4 30000000 40.0 ns/op 3 B/op 1 allocs/op