Type casting made easy



  • 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...



  • obfuscation failure: hexUnit != Table



  • 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.



  • @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. 



  • @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. 



  • @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.



  • 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...)
     



  • 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.



Log in to reply
 

Looks like your connection to What the Daily WTF? was lost, please wait while we try to reconnect.