What is a string in Go? How to find out the length of a string in characters and in bytes?

In Go, a string (string) is an immutable sequence of bytes, usually containing text in UTF-8 encoding.

• The length of a string in bytes is simply the number of bytes in the []byte slice underlying the string.
• The length of a string in characters (runes) is the number of Unicode characters, which can occupy different numbers of bytes.

Example:

package main

import (
    "fmt"
    "unicode/utf8"
)

func main() {
    s := "Привет"
    fmt.Println("Length in bytes:", len(s))
    fmt.Println("Length in characters:", utf8.RuneCountInString(s))
}

The output will be approximately:

Length in bytes: 12
Length in characters: 6

Because each Russian character in UTF-8 takes 2 bytes.