Reverse string

Sometimes in programs we want to reverse the characters in a string. This can generate a key from existing data. A string cannot be directly sorted.

Instead, we must act on the string at the level of its runes or bytes. Runes in Go are most similar to characters. We can convert strings to rune slices and then reverse those.

Example func

Let us start. Here we introduce the reverse() method. This method receives a string and returns another string. We begin by converting the string argument to a slice of runes.

package main

import "fmt"

func reverse(value string) string {
    // Convert string to rune slice.
    // ... This method works on the level of runes, not bytes.
    data := []rune(value)
    result := []rune{}

    // Add runes in reverse order.
    for i := len(data) - 1; i >= 0; i-- {
        result = append(result, data[i])
    }

    // Return new string.
    return string(result)
}

func main() {
    // Test our method.
    value1 := "cat"
    reversed1 := reverse(value1)
    fmt.Println(value1)
    fmt.Println(reversed1)

    value2 := "abcde"
    reversed2 := reverse(value2)
    fmt.Println(value2)
    fmt.Println(reversed2)
}
cat
tac
abcde
edcba

Some notes

In Go, we can access the bytes of a string instead of converting the string to a rune slice. And we can reverse these bytes.

Strings can be manipulated in many ways by first converting them to rune slices. We can reorder or modify runes. This is powerful, versatile, and can be used to reverse strings.