Strings and runes

Context

In Go, a string is a read‑only slice of bytes. It can contain arbitrary bytes, but typically holds UTF‑8 encoded text.

A rune is an int32 representing a Unicode code point. It is used to handle characters that may be more than one byte long (e.g., é, 世).

Example

Iterate over a string by bytes vs by runes.

Code example

package main

import "fmt"

func main() {
    s := "Hello, 世界"

    fmt.Println("Bytes:")
    for i := 0; i < len(s); i++ {
        fmt.Printf("%x ", s[i])
    }
    fmt.Println()

    fmt.Println("Runes:")
    for i, r := range s {
        fmt.Printf("%d: %c (%U)\n", i, r, r)
    }
}

Output

Bytes:
48 65 6c 6c 6f 2c 20 e4 b8 96 e7 95 8c
Runes:
0: H (U+0048)
1: e (U+0065)
2: l (U+006C)
3: l (U+006C)
4: o (U+006F)
5: , (U+002C)
6:   (U+0020)
7: 世 (U+4E16)
10: 界 (U+754C)

Useful links

• Strings, bytes, runes and characters in Go
• Go by Example: Strings and Runes