c# - Combine 2 numbers in a byte -

i have 2 numbers (going 0-9) , want combine them 1 byte. number 1 take bit 0-3 , number 2 has bit 4-7.

example : have number 3 , 4.
3 = 0011 , 4 0100.
result should 0011 0100.

how can make byte these binary values?

this have :

    public byte combinepindigit(int digita, int digitb)     {         bitarray digit1 = new bitarray(convert.tobyte(digita));         bitarray digit2 = new bitarray(convert.tobyte(digitb));          bitarray combined = new bitarray(8);         combined[0] = digit1[0];         combined[1] = digit1[1];         combined[2] = digit1[2];         combined[3] = digit1[3];            combined[4] = digit2[0];         combined[5] = digit2[1];         combined[6] = digit2[2];         combined[7] = digit2[3];     } 

with code have argumentoutofboundsexceptions

forget bitarray stuff.

just this:

byte result = (byte)(number1 | (number2 << 4)); 

and them back:

int number1 = result & 0xf; int number2 = (result >> 4) & 0xf; 

this works using << , >> bit-shift operators.

when creating byte, shifting number2 left 4 bits (which fills lowest 4 bits of results 0) , use | or bits unshifted bits of number1.

when restoring original numbers, reverse process. shift byte right 4 bits puts original number2 original position , use & 0xf mask off other bits.

this bits number1 in right position (since never shifted them) need mask off other bits, again & 0xf.

you should verify numbers in range 0..9 before doing that, or (if don't care if they're out of range) can constrain them 0..15 anding 0xf:

byte result = (byte)((number1 & 0xf) | ((number2 & 0xf) << 4));