Golang performance benchmark sample code

string_op_benchmark.go

package main

import (
	"strings"
)

func replaceChar1(str string, ch, replaceCh byte) string {
	var result string
	for i := 0; i < len(str); i++ {
		if str[i] == ch {
			result = result + string(replaceCh)
		} else {
			result = result + string(result[i])
		}
	}
	return result
}

func replaceChar2(str string, ch, replaceCh byte) string {
	bytes := []byte(str)
	for i := 0; i < len(str); i++ {
		if bytes[i] == ch {
			bytes[i] = replaceCh
		}
	}
	return string(bytes)
}

func replaceChar3(str string, ch, replaceCh byte) string {
	var strBuilder strings.Builder
	strBuilder.Grow(len(str))

	for i := 0; i < len(str); i++ {
		if str[i] == ch {
			strBuilder.WriteByte(replaceCh)
		} else {
			strBuilder.WriteByte(str[i])
		}
	}
	return strBuilder.String()
}

func main() {
}

string_op_benchmark_test.go

package main

import (
	"strings"
	"testing"
)

func generateString(n int) string {
	var b strings.Builder
	b.Grow(n)
	for i := 0; i < n; i++ {
		b.WriteRune('a')
	}
	return b.String()
}

func BenchmarkStringReplace1(b *testing.B) {
	n := 100_000
	str := generateString(n)

	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		replaceChar1(str, 'a', 'b')
	}
}

func BenchmarkStringReplace2(b *testing.B) {
	n := 100_000
	str := generateString(n)

	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		replaceChar2(str, 'a', 'b')
	}
}

func BenchmarkStringReplace3(b *testing.B) {
	n := 100_000
	str := generateString(n)

	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		replaceChar3(str, 'a', 'b')
	}
}