Character Sets

ASCII §

128 characters, one byte per character.

Extended ASCII §

256 characters, one byte per character.

Unicode §

a = 97 b = 98 c = 99 ... z = 122

Two bytes per character.

Convert Char to number §

"1234"[3] - '0' == 4

Char to Index §

"apple"[0] - 'a' == 0

Number Range §

'0'.toInt() == 48
'9'.toInt() = 57

e.g.:

fun parseInt(string: String): Int {  
    var num = 0  
  
 	string.forEach {  
 		if (it.toInt() in 48..57) {  
            num = num * 10 + (it - 48).toInt()  
        } else {  
            throw NumberFormatException("Invalid character $it")  
        }  
    }  
  
 	return num  
}