Go built-in benchs

bench_test.go

var (
	testString       = "xkjXS98XarHFzP1DQu03fJTLQQ7raCvoSKwlAjtTUgxZIbRt9OoAQyByESBXFYnxoHetPiZdfLHUDSh6ix1MQ2hUWKli2c79RPCjJd8weljUMh7XjIToFjU7W67gYDwMAtihxI5twI33hL6Bran4wclJcOGZVmlkASofpsPSWmsR3PS8p01rrVxcCvuSXuyIQa0JMrLI"
	testStringsSlice = make([]struct{}, 1000)
)

// 69.4 ns/op
func BenchmarkForString(b *testing.B) {
	for i := 0; i < b.N; i++ {
		for j := 0; j < len(testString); j++ {
			if testString[j] == '0' {
			}
		}
	}
}

// 168 ns/op
func BenchmarkForRangeString(b *testing.B) {
	for i := 0; i < b.N; i++ {
		for j := range testString {
			if testString[j] == '0' {
			}
		}
	}
}

// 280 ns/op
func BenchmarkForStringsSlice(b *testing.B) {
	for i := 0; i < b.N; i++ {
		for j := 0; j < len(testStringsSlice); j++ {
			if testStringsSlice[j] == struct{}{} {
			}
		}
	}
}

// 280 ns/op
func BenchmarkForRangeStringsSlice(b *testing.B) {
	for i := 0; i < b.N; i++ {
		for j := range testStringsSlice {
			if testStringsSlice[j] == struct{}{} {
			}
		}
	}
}