Find fastest method to get length in golang

test2.go

package main

import (
	"testing"
)

var smallInt = []int{1, 32, 102, 47, 2222, 986, 0, 2}
var bigInt = []int{
	1234567890, 123456789, 123456789012, 123, 1,
	12, 12345667801234, 1234567890123, 1234, 12345678901,
	123456789012345, 1234567890123456, 12345678, 1234567, 12345,
	123456,
}

// func BenchmarkGetLen(b *testing.B) {
// 	for i := 0; i < b.N; i++ {
// 		val := len(strconv.Itoa(smallInt[i&7]))
// 		_ = val
// 	}
// }

// func BenchmarkGetLenFormatInt(b *testing.B) {
// 	for i := 0; i < b.N; i++ {
// 		val := len(strconv.FormatInt(int64(smallInt[i&7]), 10))
// 		_ = val
// 	}
// }

// func BenchmarkGetLenSprint(b *testing.B) {
// 	for i := 0; i < b.N; i++ {
// 		val := len(fmt.Sprint(smallInt[i&7]))
// 		_ = val
// 	}
// }

// func BenchmarkGetLenSprintf(b *testing.B) {
// 	for i := 0; i < b.N; i++ {
// 		val := len(fmt.Sprintf("%d", smallInt[i&7]))
// 		_ = val
// 	}
// }

// func BenchmarkGetLenBig(b *testing.B) {
// 	for i := 0; i < b.N; i++ {
// 		val := len(strconv.Itoa(bigInt[i&15]))
// 		_ = val
// 	}
// }

// func BenchmarkGetLenFormatIntBig(b *testing.B) {
// 	for i := 0; i < b.N; i++ {
// 		val := len(strconv.FormatInt(int64(bigInt[i&15]), 10))
// 		_ = val
// 	}
// }

// func BenchmarkGetLenSprintBig(b *testing.B) {
// 	for i := 0; i < b.N; i++ {
// 		val := len(fmt.Sprint(bigInt[i&15]))
// 		_ = val
// 	}
// }

// func BenchmarkGetLenSprintfBig(b *testing.B) {
// 	for i := 0; i < b.N; i++ {
// 		val := len(fmt.Sprintf("%d", bigInt[i&15]))
// 		_ = val
// 	}
// }

func BenchmarkGetLenDivide(b *testing.B) {
	for i := 0; i < b.N; i++ {
		ret := smallInt[i&7]
		val := 1
		for ret > 9 {
			ret /= 10
			val++
		}
		_ = val
	}
}
func BenchmarkGetLenDivideBig(b *testing.B) {
	for i := 0; i < b.N; i++ {
		ret := bigInt[i&15]
		val := 1
		for ret > 9 {
			ret /= 10
			val++
		}
		_ = val
	}
}

var res = [20]int{
	0, 10, 100, 1000, 10000, 100000, 1000000, 10000000, 100000000, 1000000000, 10000000000,
	100000000000, 1000000000000, 10000000000000, 100000000000000, 1000000000000000, 10000000000000000, 100000000000000000, 1000000000000000000, (1 << 63) - 1,
}

func countLength(num int) int {
	val := 0
	if num >= 10000 {
		val = 4
	}
	if num >= 1000000000 {
		val = 9
	}
	for ; val < 19; val++ {
		if num >= res[val] {
			return val + 1
		}
	}
	return 1
}

func countLengthNoPrep(num int) int {
	for val := 0; val < 19; val++ {
		if num >= res[val] {
			return val + 1
		}
	}
	return 1
}

func BenchmarkGetLenLookUpTable(b *testing.B) {
	for i := 0; i < b.N; i++ {
		val := countLength(smallInt[i&7])
		_ = val
	}
}

func BenchmarkGetLenLookUpTable2(b *testing.B) {
	for i := 0; i < b.N; i++ {
		val := countLengthNoPrep(smallInt[i&7])
		_ = val
	}
}

func BenchmarkGetLenLookUpTableBig(b *testing.B) {
	for i := 0; i < b.N; i++ {
		val := countLength(bigInt[i&15])
		_ = val
	}
}

func BenchmarkGetLenLookUpTableBig2(b *testing.B) {
	for i := 0; i < b.N; i++ {
		val := countLengthNoPrep(bigInt[i&15])
		_ = val
	}
}