Replacing multiple bytes in a byte array

Question

I have a byte array like so

 var byteArray = new byte[]
        {
            0x9C, 0x50, 0x53, 0x51, 0x52, 0x41, 0x50, 0x41, 0x51, 0x41, 0x52, 0x41, 0x53, 
            0x48, 0x83, 0xEC, 0x28,                                                       
            0x48, 0xB9, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  // Line 3                 
            0x48, 0xB8, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  // Line 4                  
            0xFF, 0xD0,                                                                   
            0x48, 0x83, 0xC4, 0x28,                                                       
            0x41, 0x5B, 0x41, 0x5A, 0x41, 0x59, 0x41, 0x58, 0x5A, 0x59, 0x5B, 0x58,0x9D,  
            0xC3                                                                          
        };

I want to replace the following bytes on line 3

0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00

As well as the following bytes on line 4

0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00

With different bytes (other than 0x00)

Note that the bytes I want to change on line 3 are different to the bytes I want to change on line 4

What is the simplest way to accomplish this?

Answer 1

If you don't want / can't modify your source array, you can easily create another one with same values :

byte[] copyArray;
byteArray.CopyTo(copyArray, 0);
// or
copyArray = byteArray.ToArray() // following @Matthew Watson

Then if you want to change your eigth last values for line 3 :

byte[] ReplaceThirdLineValues(byte[] source, params byte[] newValues)
{
    byte[] copyArray;
    byteArray.CopyTo(source, 0);

    for (int i = 0 ; i < newValues.Length && i < 8 ; i++)
    // i < 8 because in your array there are 8 0x00 in a row
        if (copyArray[19 + i] == 0x00 && newValues[i] > 0x00)
        // newValues[i] > 0x00, so if you do not want to override value,
        // just give 0x00 to your parameter
            copyArray[19 + i] = newValues[i];
}

For your fourth line, replace copyArray[19 + i] by copyArray[29 + i]

byte[] copyArray = ReplaceThirdLineValues(byteArray, 0x01, 0x02, 0x03, 0x04);