Tell us about byte and rune in Go, what is the difference, and give an example with string reversal.

In Go, byte is an alias for uint8, used to represent a single byte of data, often for ASCII characters. rune is an alias for int32, representing a Unicode code point, i.e., a character in UTF-8 encoding.

The difference is that byte is just a byte, while rune is a character that can occupy multiple bytes in UTF-8.

Example of reversing a string considering Unicode:

package main

import "fmt"

func reverse(s string) string {
    runes := []rune(s) // convert string to a slice of runes
    for i, j := 0, len(runes)-1; i < j; i, j = i+1, j-1 {
        runes[i], runes[j] = runes[j], runes[i]
    }
    return string(runes)
}

func main() {
    s := "Привет, мир!"
    fmt.Println(reverse(s)) // !рим ,тевирП
}

This way, we correctly handle multi-byte characters, unlike reversing by bytes, which can break UTF-8.