C#: How to bit shift hexadecimal digits

Question

Okay, I am working on a card playing program, and I am storing card values as hexadecimal digits. Here is the array:

 public int[] originalCards = new int[54]
        {
            0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, 0x1B, 0x1C, 0x1D,
            0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, 0x2D,
            0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, 0x3D,
            0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49, 0x4A, 0x4B, 0x4C, 0x4D,
            0x50, 0x51
        };

The first digit refers to the suit (1 = spades; 2 = clubs; .... 5 = Jokers) The second digit is the number of the card (1 = ace, 5 = 5; 13 = K, etc).

I would like to do something like the following:

Pseudocode: public int ReturnCard(int num) { int card = currentDeck[num]; int suit = card.firsthexdigit; int value = card.secondhexdigit; return 0; }

 Pseudocode:  public int ReturnCard(int num) { int card = currentDeck[num]; int suit = card.firsthexdigit; int value = card.secondhexdigit; return 0; } 

I don't need a new method to work on ints, I just included it for clarity's sake.

Anybody know how to do this in C#?

Edit: Okay, I am using bit shifting as described in one of the answers. I can get the second digit (the suit) just fine, but the first digit keeps coming out as '0'. Any idea why?

Edit:edit: okay, works fine now. Thanks guys.

Answer 1

You're not really "parsing" as such, just doing some simple bit manipulation.

int card = currentDeck[num];
int suit = (card & 0xF0) >> 4;
int value = card & 0x0F;

Will do what you want.

Answer 2

Here's an answer using bit fields.

struct {
    unsigned int suit:4;
    unsigned int value:4;
} card    = currentDeck[num];
int suit  = card.suit;
int value = card.value;

You may need to add in int for padding as either the first or last field to line the bits up properly. Bit fields are normally used to access hardware because hardware registers frequently pack multiple flags into a single byte.

By the way if you use the bit shift, you want to shift by the number of bits in a hexadecimal digit. One hex digit holds values 0 - 15 or 0 - F, this requires 4 bits not 8. So this should be used:

int suit = (card & 0xF0) >> 4;

Answer 3

To answer your question about the use of 0xF0 and 0x0F in the bit shift example what they are doing is a bitwise AND . When you do card & 0xF0 what you are doing is anding the two values, this results in setting all bits except the 4 you are interested in to 0 . Ex:

 0x48   01001000     0x48   01001000
&0x0F  &00001111    &0xF0  &11110000
-----   --------     ----   --------
 0x08   00001000     0x48   01000000 >> 4
                            --------
                            00000100

Answer 4

You can try

int card = originalCards[1];
int suit = card /16;
int value = card % 16; 

Answer 5

Here is a working example:

using System;

namespace Test
{
    class MainClass
    {
        static int[] currentDeck = new int[54] {
                0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, 0x1B, 0x1C, 0x1D,
                0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, 0x2D,
                0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, 0x3D,
                0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49, 0x4A, 0x4B, 0x4C, 0x4D,
                0x50, 0x51 };

        static void printParts (int num)
        {
            int card  = currentDeck[num];
            int suit  = (card & 0xF0) >> 4;
            int value = (card & 0x0F);

            Console.Out.WriteLine(
                    String.Format ("Card: {0:x4},   ", card) +
                    String.Format ("Suit: {0:x4},   ", suit) +
                    String.Format ("Value: {0:x4}", value ));
        }


        public static void Main (string[] args)
        {
            printParts(  7 );
            printParts( 18 );
            printParts( 30 );
            printParts( 48 );
        }
    }
}

This produces the following:

Card: 0018,   Suit: 0001,   Value: 0008
Card: 0026,   Suit: 0002,   Value: 0006
Card: 0035,   Suit: 0003,   Value: 0005
Card: 004a,   Suit: 0004,   Value: 000a

I'm not sure why your upper digits are not correct.