How to convert char to ascii value in kotlin language

Question

I am developing an android application with kotlin in which I need to convert an string character to its ASCII value,

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.toInt()).toString()            
        }
       return originalText
}

this tutorial website showed me to use char.toInt() but it gives runtime error saying

Caused by: java.lang.NumberFormatException: Invalid int: "u"

so how if anyone knows hot to convert char to ASCII value please help me.

Answer 1

char.value is a String . When you call String.toInt() , it is expecting a numeric string such as "1", "-123" to be parsed to Int . So, "f".toInt() will give you NumberFormatException since "f" isn't a numeric string.

If you are sure about char.value is a String containing exactly one character only. To get the ascii value of it, you can use:

char.value.first().code

Answer 2

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()
}

Answer 3

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.

Answer 4

如果您的变量是 char 类型，例如“a”，您可以简单地使用 a.code