CODEWITHSUNDEEP
kotlin
d-feverx
d-feverx

Reputation: 1672

Check if a string contains only letters

How I can make a function that take a string and return the result whether the string contain alphabet letter only or not.

Upvotes: 2

Views: 9514

Answers (4)

Sam
Sam

Reputation: 381

You could use a simple regular expression to validate the input:

fun isOnlyLetters(word: String): Boolean {
val regex = "^[A-Za-z]*$".toRegex()
return regex.matches(word)}

Alternatively,

  • making the regex ^[A-Za-z ]*$ (space after "z")would allow any amount of whitespace (such as in a phrase) at any point in the string (i.e. and still return true).
  • making the regex ^[A-Za-z ]+$ (* -> +) would return false for an empty string(i.e. ensure that there is at least one character in the input, be it a letter or space).

Upvotes: 3

IR42
IR42

Reputation: 9672

function all returns true if all characters match the given predicate.

fun String.onlyLetters() = all { it.isLetter() }

if (str.onlyLetters()) {
// only letters
}
else {

}

Upvotes: 9

forpas
forpas

Reputation: 164089

You can use the function firstOrNull() to search for the 1st non letter char and compare the result with null:

fun onlyLetters(s: String): Boolean = (s.firstOrNull { !it.isLetter() } == null)

or as an extension function:

fun String.onlyLetters(): Boolean = (firstOrNull { !it.isLetter() } == null)

Note that this way you will get true even if the string is empty.
If you don't want this then you should add another condition for the length like:

fun String.onlyLetters(): Boolean = length > 0 && (firstOrNull { !it.isLetter() } == null)

Upvotes: 4

d-feverx
d-feverx

Reputation: 1672

create an extension function isLettersOnly()

/* * This fuction return true only if the string contain a-z or A-Z, * Otherwise false*/

fun String.isLettersOnly(): Boolean {
    val len = this.length
    for (i in 0 until len) {
        if (!this[i].isLetter()) {
            return false
        }
    }
    return true
}

1.check a string value

fun main() {
    val text = "name"

    if (text.isLettersOnly()) {
        println("This is contain a-z,A-Z only")
    } else {
        println("This contain something else")

    }
}

output: This is contain a-z,A-Z only

2.check a string value

fun main() {
    val text = "name 5"

    if (text.isLettersOnly()) {
        println("This is contain a-z,A-Z only")
    } else {
        println("This contain something else")

    }
}

output: This contain something else

Upvotes: 0

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