Count golang number size

The easiest way is to convert with Itoa() to text and get the characters with len() . But you can also do mathematically (module math ).

package main
import ("fmt"
        "strconv"
        "math")

func main() {
    t := strconv.Itoa(57890)
    fmt.Println("Tamanho matematicamente calculado:", math.Floor(math.Log10(math.Abs((57890)))) + 1)
    for i := 0; i < len(t); i++ {
        fmt.Printf("%c\n", t[i])
    }
}

See running on ideone . And at Coding Ground . Also put it on GitHub for future reference .

I got element 2 because the index starts at 0, so the third is number 2.

Note that conversions are not necessary as there will be only ASCII characters.

For the first case, use the strconv method. Itoa() " to convert the numeric value to string and method len() to check the file size. For the second situation, use rune(str)[position] in which, position represents the position of the string passed as parameter. Remember that you said 3 position, however since the vector starts with 0 , the return relative to the 3 position would be 9 . See:

package main
import ("fmt"
        "strconv")

func main() {
    str := strconv.Itoa(57890)
    fmt.Println(len(str))

    // index inicia com 0. então 2 representa a posição 3
    fmt.Println(string([]rune(str)[0])) // saida 5
    fmt.Println(string([]rune(str)[1])) // saida 7
    fmt.Println(string([]rune(str)[2])) // saida 8
}

See funfando no play golang .