How to convert char to ascii value in kotlin language

Since Kotlin 1.5

if your variable is of type char for example 'a' you can simply use a.code.

The old methods (e.g. toByte()) are deprecated now.

You said ascii, not unicode. So it's easy.

This is an example that shows you how to convert a char ('A') to it's ascii value.

fun main(vararg args: String) {
  println('A'.toByte().toInt())
}

The output is what we expected, 65.

Note this doesn't work with unicode.

Edit 1

I guess this to work.

fun tryDiCript(cypher: String): String {
    var cypher = "fs2543i435u@$#g#@#sagb@!#12416@@@"
    var originalText = ""

    var regEx = Regex("[a-z]")
    for(char in regEx.findAll(cypher))
        originalText += char.value[0].toInt().toString()            
    return originalText
}

And I recommend you to use StringBuilder.

fun tryDiCript(cypher: String): String {
    var cypher = "fs2543i435u@$#g#@#sagb@!#12416@@@"
    val originalText = StringBuilder()

    var regEx = Regex("[a-z]")
    for(char in regEx.findAll(cypher))
        originalText.append(char.value[0].toInt())
    return originalText.toString()
}

I checked @ice1000's answer, I found the block below does not work.

fun main(vararg args: String) {
  println('A'.toByte().toInt())
}

As we can see in the Kotlin Documentation String - Kotlin Programming Language,the toByte() function of String "Parses the string as a signed Byte number and returns the result." If the the content of the string is not a number, it will throw a java.lang.NumberFormatException.

But there is another function of String called toByteArray(),this function does no require the content of the string being numbers. My code is as following:

String tempString = "Hello"
val tempArray = tempString.toByteArray()
for (i in tempArray){
    println(i.toInt())
}

Attention that toByteArray() function's definition in kotlin's documentaion:

fun String.toByteArray(
    charset: Charset = Charsets.UTF_8
): ByteArray

The default charset is UTF-8, if you would like to use other charset, you can modify it with the parameter.