Can't create socket on Windows

Question

I have quite an embarrassing problem. The following code simply will not create a socket on Windows; it fails and displays the error message. Could anyone briefly explain why this might be? I'm incredibly confused and frustrated that something so simple is failing. Thank you.

int sock;
if( (sock = socket(AF_INET, SOCK_STREAM, 0)) < 0 )
{
    printf("error opening socket");
}

EDIT: Also, printing out strerror(errno) simply shows "No error".

Answer 1

You need to call WSAStartup() before any other socket functions will work on Windows (and you're supposed to call WSACleanup() when you're done).

Answer 2

Jerry Coffin is right about WSAStartup() and WSACleanup().

Also note that this code

if( (sock = socket(AF_INET, SOCK_STREAM, 0)) < 0 )

is problematic because SOCKET is an unsigned type (unsigned int).

From winsock.h

/*
 * This is used instead of -1, since the
 * SOCKET type is unsigned.
 */
#define INVALID_SOCKET  (SOCKET)(~0)
#define SOCKET_ERROR            (-1)

So, IMO it's better to replace that line with

if( INVALID_SOCKET == (sock = socket(AF_INET, SOCK_STREAM, 0)) )

even if it's not the root cause.