Check If the Rune is a Letter or not in Golang

Rune is a superset of ASCII or it is an alias of int32. It holds all the characters available in the world’s writing system, including accents and other diacritical marks, control codes like tab and carriage return, and assigns each one a standard number. This standard number is known as a Unicode code point or rune in the Go language.
You are allowed to check the given rune is a letter or not with the help of IsLetter() function. This function returns true if the given rune is a letter, or return false if the given rune is not a letter. This function is defined under Unicode package, so for accessing this method you need to import the Unicode package in your program.

Syntax:

func IsLetter(r rune) bool

The return type of this function is boolean. Let us discuss this concept with the help of given examples:

Example 1:

// Go program to illustrate how to
// check the given rune is a letter
package main

import (
    "fmt"
    "unicode"
)

// Main function
func main() {

    // Creating rune
    rune_1 := 'g'
    rune_2 := 'e'
    rune_3 := '1'
    rune_4 := '4'
    rune_5 := 'S'

    // Checking the given rune
    // is a letter or not
    // Using IsLetter() function
    res_1 := unicode.IsLetter(rune_1)
    res_2 := unicode.IsLetter(rune_2)
    res_3 := unicode.IsLetter(rune_3)
    res_4 := unicode.IsLetter(rune_4)
    res_5 := unicode.IsLetter(rune_5)

    // Displaying results
    fmt.Println(res_1)
    fmt.Println(res_2)
    fmt.Println(res_3)
    fmt.Println(res_4)
    fmt.Println(res_5)

}

Output:

true
true
false
false
true

Example 2:

// Go program to illustrate how to
// check the given rune is a letter
package main

import (
    "fmt"
    "unicode"
)

// Main function
func main() {

    // Creating a slice of rune
    val := []rune{'g', 'E', '3', 'K', '1'}

    // Checking each element of the given
    // slice of the rune is a letter or not
    // Using IsLetter() function
    for i := 0; i < len(val); i++ {

        if unicode.IsLetter(val[i]) == true {

            fmt.Println("It is a letter")

        } else {

            fmt.Println("It is not a letter")
        }
    }
}

Output:

It is a letter
It is a letter
It is not a letter
It is a letter
It is not a letter