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pythoncsocketstypeerrorhtonl

Python socket: cannot receive int array

I try to make a inter process communication between a Python and c program via winsockets. Sending a string does work, but now I try to send an int array from the c socket to the python socket.

I already found out that I have to use htonl() to convert the int array into a byte stream as the send function of winsock2 cannot send int arrays directly.

Now I want to use ntohl() in the python socket but the receive function returns bytes whereas ntohl() needs an integer value as input.

Here is my code

C-Side (just relevant parts):

uint32_t a[1] = {1231};
uint32_t a_converted[1]={0};
a_converted[0] = htonl(a[0]);
iResult = send( ConnectSocket, ( char *)   a_converted, sizeof( a_converted), 0 );

Python Side (just relevant parts):

data = connection.recv(16)
data_i = socket.ntohl(data)
Solution

  • What you received is string of bytes, did not ntohl cause exception? You may use struct module to unpack - for 16 bytes

    struct.unpack('!4I', data)

    Meaning - unpack 4 unsigned 32-bit integers in network order

    RTM

    (I cannot test it - try it on your own)

    EDIT: Ooops, did not read your comment through. According to sockets docs, recv should return object of type bytes. If it returns object of type str - you should convert it to bytes - in Python3 it would be data.encode()

    PS Which Python are you on?