C# Replace bytes in Byte[]

You could program it…. try this for a start… this is however not robust not production like code yet…beaware of off-by-one errors I didn’t fully test this…

    public int FindBytes(byte[] src, byte[] find)
    {
        int index = -1;
        int matchIndex = 0;
        // handle the complete source array
        for(int i=0; i<src.Length; i++)
        {
            if(src[i] == find[matchIndex])
            {
                if (matchIndex==(find.Length-1))
                {
                    index = i - matchIndex;
                    break;
                }
                matchIndex++;
            }
            else if (src[i] == find[0])
            {
                matchIndex = 1;
            }
            else
            {
                matchIndex = 0;
            }

        }
        return index;
    }

    public byte[] ReplaceBytes(byte[] src, byte[] search, byte[] repl)
    {
        byte[] dst = null;
        int index = FindBytes(src, search);
        if (index>=0)
        {
            dst = new byte[src.Length - search.Length + repl.Length];
            // before found array
            Buffer.BlockCopy(src,0,dst,0, index);
            // repl copy
            Buffer.BlockCopy(repl,0,dst,index,repl.Length);
            // rest of src array
            Buffer.BlockCopy(
                src, 
                index+search.Length , 
                dst, 
                index+repl.Length, 
                src.Length-(index+search.Length));
        }
        return dst;
    }

Implement as an extension method

public void Replace(this byte[] src, byte[] search, byte[] repl)
{
      ReplaceBytes(src, search, repl);
}

usage normal method:

ReplaceBytes(bytesfromServer, 
             new byte[] {0x75, 0x83 } , 
             new byte[]{ 0x68, 0x65, 0x6c});

Extension method usage:

bytesfromServer.Replace(
             new byte[] {0x75, 0x83 }, 
             new byte[]{ 0x68, 0x65, 0x6c});