Question

I am working on a network programming on linux machine using C++ and I was wondering how I can set 4 bytes bit pattern for magic number in Java (client). Also how do I set the same bit pattern in c++ co I can compare the one from client with the one on the server side.

Thank in advance..

Edit

So now I have this

    byte[] signature = new byte[4];

    for(int i=0; i<4; i++){
        signature[i] = (byte) 0xA9;
    }

And if I looked at the inside of the array after for loop from the debugger then I have

{-89, -89, -89, -89}

And I did something like this in C++

    uint8_t m_magicNumberBuffer[4];
    magicKeyRead = read(m_fd, m_magicNumberBuffer, SIZE_OF_HEADER);


    if(m_magicNumberBuffer[0] == 0xA9 && m_magicNumberBuffer[1] == 0xA9 && m_magicNumberBuffer[2] == 0xA9 && m_magicNumberBuffer[3] == 0xA9){
        printf("SocketClient::recvMagicKey, Magic key has been found \n");
        break;
    }

I somehow works but not sure that I have declared m_magicNumberBuffer and unsigned integer but those were in negative 89 in java. Is this ok to do this in this way?

Thanks in advance.

Answer 1

Java has bitwise operators, for example bitwise OR |, bitwise AND & and bit shift operators >>>, >> and <<, very similar to what C++ has. You can use those to manipulate bits exactly as you want.

Since you don’t explain in more detail what you want to do, I cannot give you a more detailed answer.