Example 1: Kotlin Program to Check Alphabet using if else

fun main(args: Array<String>) {

    val c = '*'

    if (c >= 'a' && c <= 'z' || c >= 'A' && c <= 'Z')
        println("$c is an alphabet.")
    else
        println("$c is not an alphabet.")
}

When you run the program, the output will be:

* is not an alphabet.

Like Java, in Kotlin, char variable stores the ASCII value of a character (number between 0 and 127) rather than the character itself.

The ASCII value of lowercase alphabets are from 97 to 122. And, the ASCII value of uppercase alphabets are from 65 to 90.

This is the reason, we compare variable c between ‘a’ (97) to ‘z’ (122). Likewise, we do the same to check for uppercase alphabets between ‘A’ (65) to ‘Z’ (90).

You can use ranges instead of comparisons to solve this problem.

Example 2: Kotlin Program to Check Alphabet using if else with ranges

fun main(args: Array<String>) {

    val c = 'a'

    if (c in 'a'..'z' || c in 'A'..'Z')
        println("$c is an alphabet.")
    else
        println("$c is not an alphabet.")
}

When you run the program, the output will be:

a is an alphabet.

You can even use when expression instead of if else to solve the problem.

Example #: Kotlin Program to Check Alphabet using when

fun main(args: Array<String>) {

    val c = 'C'

    when {
        (c in 'a'..'z' || c in 'A'..'Z') -> println("$c is an alphabet.")
        else -> println("$c is not an alphabet.")
    }
}

When you run the program, the output will be:

C is an alphabet.