Sample code for 30+ languages & platforms
C

Check Whether a Socket Is Writable

See more Socket/SSL/TLS Examples

Demonstrates Socket.CheckWriteable, which waits for the connected socket to become writable. It returns 1 if writable, 0 if it did not become writable before the timeout, or -1 on error.

Background. A maxWaitMs of 0 performs a nonblocking poll. This is useful for flow control before attempting a large send.

Chilkat C Downloads

C
#include <C_CkSocket.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkSocket socket;
    BOOL bTls;
    int maxWaitMs;
    int writable;

    success = FALSE;

    socket = CkSocket_Create();

    //  Connect to the server using TLS.
    bTls = TRUE;
    maxWaitMs = 5000;
    success = CkSocket_Connect(socket,"example.com",5000,bTls,maxWaitMs);
    if (success == FALSE) {
        printf("%s\n",CkSocket_lastErrorText(socket));
        CkSocket_Dispose(socket);
        return;
    }

    //  Wait up to 5 seconds for the socket to become writable.  Returns 1 if writable, 0 if it did not
    //  become writable before the timeout, or -1 on error.
    writable = CkSocket_CheckWriteable(socket,5000);
    if (writable < 0) {
        printf("%s\n",CkSocket_lastErrorText(socket));
        CkSocket_Dispose(socket);
        return;
    }

    if (writable != 1) {
        printf("The socket did not become writable before the timeout.\n");
        CkSocket_Dispose(socket);
        return;
    }

    printf("The socket is writable.\n");


    CkSocket_Dispose(socket);

    }