Converting string to decimal character array in Apex

Recently I had to find a way to convert strings into their ascii decimal value. I solved this by converting to hex first, and then using some simple math to get the decimal value of each character. This won’t work on double byte characters, but that wasn’t my use case so for now this will work for me.

Edit: After some thinking, making this double byte or even multiple byte wouldn’t be too hard if you were to figure out the ratio of input length to hex output length, then increase the formula to increase the power of 16. I’ll try to get back to this later this week and update for those using multi byte characters.

Edit2: After more investigation and learning the ins and outs of UTF8 I now fully understand the return values of the EncodingUtil.convertToHex method. It returns bytes in UTF8 format. Each byte explains how many bytes that character uses. Some bytes use 1 (old school ascii compatible 0-127), some use 2, 3 or even 4. The range in the first byte tells a story about that character. I have a method to convert these to decimals that can be parsed by String.fromCharArray if anyone is interested. So since each byte is encoded in this, this technically handles UTF8 just fine, and works perfect for my apex ported AES encryption :-)

private static Map<String,Integer> hexMap = new Map<String,Integer>();
static {
	hexMap.put('0',0);
	hexMap.put('1',1);
	hexMap.put('2',2);
	hexMap.put('3',3);
	hexMap.put('4',4);
	hexMap.put('5',5);
	hexMap.put('6',6);
	hexMap.put('7',7);
	hexMap.put('8',8);
	hexMap.put('9',9);
	hexMap.put('A',10);
	hexMap.put('B',11);
	hexMap.put('C',12);
	hexMap.put('D',13);
	hexMap.put('E',14);
	hexMap.put('F',15);
	hexMap.put('a',10);
	hexMap.put('b',11);
	hexMap.put('c',12);
	hexMap.put('d',13);
	hexMap.put('e',14);
	hexMap.put('f',15);
}

public static List<Integer> stringToInt(String input) {
	String hex = EncodingUtil.convertToHex(Blob.valueOf(input));
	List<Integer> retValues = new List<Integer>();

	for(Integer i=0;i<hex.length();i+=2) {
		retValues.add( (hexMap.get(hex.substring(i,i+1))*16) + (hexMap.get(hex.substring(i+1,i+2))) );
	}
	return retValues;
}