How to convert uint8 to string

Question

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]))
}

Example

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?

Godthaab

Check the first part of this answer if you are looking for information about slices of uint8 ([]uint8): https://mcmap.net/q/56917/-how-to-convert-int8-to-string – Jakejakes

string(u) or fmt.Sprintf("%s", u) to set []uint8 to a sting. See https://mcmap.net/q/56302/-how-to-convert-uint8-to-string. []uint8("abc") to set a string to []uint8. See https://mcmap.net/q/55268/-how-can-i-convert-string-to-integer-in-golang. – Jeaninejeanlouis

Answer 1

Simply convert it :

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

Jeth

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

Bobbi

strconv.Itoa(int(s))) - is exactly what I was looking for to convert numeric representation of byte value into string – Helbonia

There is a difference between conversion and casting. But in Go, casting is not possible. Only conversion is possible in Go. – Snappish

Answer 3

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

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

Eyesight

Accepted answer is correct. As @Bobbi explains below, this method does not do what some might expect. – Jakejakes

casting using string(c) is a hack in Go which might be removed soon. See Rob Pikes response to the question on Reddit – Mirtamirth

Answer 4

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]), string(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 G, 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://mcmap.net/q/56918/-string-to-number-conversion-in-golang.

But Sprintf uses reflection. See the comment in https://mcmap.net/q/53864/-how-to-convert-an-int-value-to-string-in-go. Using Itoa (Integer to ASCII) is faster. See @DenysSéguret and https://mcmap.net/q/53864/-how-to-convert-an-int-value-to-string-in-go. Quotes edited.

Jeaninejeanlouis

A boolean, numeric, or string type can be set to another type. For float64 see https://mcmap.net/q/56303/-how-to-round-to-nearest-int-when-casting-float-to-int-in-go, int see https://mcmap.net/q/55267/-idiomatic-type-conversion-in-go, []rune see https://mcmap.net/q/56310/-golang-how-does-the-rune-function-work, string see https://mcmap.net/q/55268/-how-can-i-convert-string-to-integer-in-golang and for bool see https://mcmap.net/q/56305/-is-there-a-way-to-convert-integers-to-bools-in-go-or-vice-versa. – Jeaninejeanlouis

Answer 5

use %c

    str := "Hello"
    fmt.Println(str[1]) // 101
    fmt.Printf("%c\n", str[1])

Kenyon