Type casting made easy

omega0

private static final char[] Table =
{
	0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F,
	0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F,
	0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, 0x2D, 0x2E, 0x2F,
	0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, 0x3D, 0x3E, 0x3F,
	0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49, 0x4A, 0x4B, 0x4C, 0x4D, 0x4E, 0x4F,
	0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5A, 0x5B, 0x5C, 0x5D, 0x5E, 0x5F,
	0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6A, 0x6B, 0x6C, 0x6D, 0x6E, 0x6F,
	0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7A, 0x7B, 0x7C, 0x7D, 0x7E, 0x7F,
	0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89, 0x8A, 0x8B, 0x8C, 0x8D, 0x8E, 0x8F,
	0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9A, 0x9B, 0x9C, 0x9D, 0x9E, 0x9F,
	0xA0, 0xA1, 0xA2, 0xA3, 0xA4, 0xA5, 0xA6, 0xA7, 0xA8, 0xA9, 0xAA, 0xAB, 0xAC, 0xAD, 0xAE, 0xAF,
	0xB0, 0xB1, 0xB2, 0xB3, 0xB4, 0xB5, 0xB6, 0xB7, 0xB8, 0xB9, 0xBA, 0xBB, 0xBC, 0xBD, 0xBE, 0xBF,
	0xC0, 0xC1, 0xC2, 0xC3, 0xC4, 0xC5, 0xC6, 0xC7, 0xC8, 0xC9, 0xCA, 0xCB, 0xCC, 0xCD, 0xCE, 0xCF,
	0xD0, 0xD1, 0xD2, 0xD3, 0xD4, 0xD5, 0xD6, 0xD7, 0xD8, 0xD9, 0xDA, 0xDB, 0xDC, 0xDD, 0xDE, 0xDF,
	0xE0, 0xE1, 0xE2, 0xE3, 0xE4, 0xE5, 0xE6, 0xE7, 0xE8, 0xE9, 0xEA, 0xEB, 0xEC, 0xED, 0xEE, 0xEF,
	0xF0, 0xF1, 0xF2, 0xF3, 0xF4, 0xF5, 0xF6, 0xF7, 0xF8, 0xF9, 0xFA, 0xFB, 0xFC, 0xFD, 0xFE, 0xFF
};

public static byte[] convertByte(String data)
{
	int length = data.length();
	byte[] rv = new byte[length / 2];
	String abyte;
	int intval = 0;
	int ofst = 0;
	for (int idx = 0; idx < length; idx += 2, ofst++)
	{
	  abyte = data.substring(idx, idx + 2);
	  intval = Integer.parseInt(abyte, 16);
	  rv[ofst] = (byte)hexUnit[iChar];
	}
	return rv;
}

Am I thankful they didn't write a convertInt() or convertLong() function...

ammoQ

obfuscation failure: hexUnit != Table

smxlong

Nice. Refers to hexUnit instead of Table. Computes a useless value "intval" which is chucked. Uses some obscure index called iChar.

The best one is the Table which maps the value n to the value n. I really like that one.

ammoQ

@smxlong said:

Nice. Refers to hexUnit instead of Table. Computes a useless value "intval" which is chucked. Uses some obscure index called iChar.
The best one is the Table which maps the value n to the value n. I really like that one.

Actually it's very useful later in case the value of say 0xf3 changes.

asuffield

@ammoQ said:

@smxlong said:
Nice. Refers to hexUnit instead of Table. Computes a useless value "intval" which is chucked. Uses some obscure index called iChar.
The best one is the Table which maps the value n to the value n. I really like that one.
Actually it's very useful later in case the value of say 0xf3 changes.

Real languages like FORTRAN have built-in support for changing the value of 0xf3.

I really, really wish I was joking.

djork

@asuffield said:

@ammoQ said:
@smxlong said:
Nice. Refers to hexUnit instead of Table. Computes a useless value "intval" which is chucked. Uses some obscure index called iChar.
The best one is the Table which maps the value n to the value n. I really like that one.
Actually it's very useful later in case the value of say 0xf3 changes.
Real languages like FORTRAN have built-in support for changing the value of 0xf3.
I really, really wish I was joking.

Forth, too. All it takes is:

: 3 4 ;

And now ...

3 3 +

... yields 8! This is actually one of my favorite things about Forth: nothing is sacred.

As for the OP: The real WTF is that at first glance I thought I was looking at C.

vt_mruhlin

I'd be willing to guess that the Table was only introduced to get around the fact that ints are like 4 bytes. (byte)intval would have generated a warning when compiling, so somebody whipped that up to appease their manager.

It's pretty obviously a C programmer using Java against his will, so I don't blame him for not knowing a more natural way to do what he's trying to do. I don't either (but I do know how to google it...)

taodude

Ugh, it could be a translation table of some kind. Maybe they really are changing the value of 0xf3 and its kin, elsewhere in the prog.

Sadly, that doesn't explain the rest of the mess.