How to convert uint8 to string

Question

http://play.golang.org/p/BoZkHC8_uA

I want to convert uint8 to string but can't figure out how.

  package main

  import "fmt"
  import "strconv"

  func main() {

    str := "Hello"
    fmt.Println(str[1])  // 101

    fmt.Println(strconv.Itoa(str[1]))
  }

This gives me prog.go:11: cannot use str[1] (type uint8) as type int in function argument [process exited with non-zero status]

Any idea?

Answer 1

Simply convert it :

    fmt.Println(strconv.Itoa(int(str[1])))

Answer 2

There is a difference between converting it or casting it, consider:

var s uint8 = 10
fmt.Print(string(s))
fmt.Print(strconv.Itoa(int(s)))

The string cast prints '\n' (newline), the string conversion prints "10". The difference becomes clear once you regard the []byte conversion of both variants:

[]byte(string(s)) == [10] // the single character represented by 10
[]byte(strconv.Itoa(int(s))) == [49, 48] // character encoding for '1' and '0'

see this code in play.golang.org

Answer 3

There are no automatic conversions of basic types in Go expressions. See https://talks.golang.org/2012/goforc.slide#18. A byte (an alias of uint8) or []byte ([]uint8) has to be set to a bool, number or string.

package main

import (
    . "fmt"
)

func main() {
    b := []byte{'G', 'o'}
    c := []interface{}{b[0], float64(b[0]), int(b[0]), rune(b[0]), Sprintf("%s", b), b[0] != 0}
    checkType(c)
}

func checkType(s []interface{}) {
    for k, _ := range s {
        // uint8 71, float64 71, int 71, int32 71, string Go, bool true
        Printf("%T %v\n", s[k], s[k])
    }
}

Sprintf("%s", b) can be used to convert []byte{'G', 'o' } to the string "Go". You can convert any int type to a string with Sprintf. See https://stackoverflow.com/a/41074199/12817546.

But Sprintf uses reflection. See the comment in https://stackoverflow.com/a/22626531/12817546. Using Itoa (Integer to ASCII) is faster. See @DenysSéguret and https://stackoverflow.com/a/38077508/12817546. Quotes edited.

Answer 4

You can do it even simpler by using casting, this worked for me:

var c uint8
c = 't'
fmt.Printf(string(c))