Sample code for 30+ languages & platforms
Unicode C

Bind and Listen on an Available Port in a Range

See more Socket/SSL/TLS Examples

Demonstrates Socket.BindAndListenPortRange, which searches an inclusive port range for an available TCP port, binds it, and begins listening. It returns the selected port, or -1 on failure.

Background. This is useful when any of several ports is acceptable and the application needs to discover which one was bound.

Chilkat Unicode C Downloads

Unicode C
#include <C_CkSocketW.h>

void ChilkatSample(void)
    {
    HCkSocketW socket;
    int boundPort;

    socket = CkSocketW_Create();

    //  Search the inclusive port range for an available TCP port, bind it, and begin listening.  The
    //  method returns the selected port, or -1 when no port can be bound.
    boundPort = CkSocketW_BindAndListenPortRange(socket,5000,5100,25);
    if (boundPort < 0) {
        wprintf(L"%s\n",CkSocketW_lastErrorText(socket));
        CkSocketW_Dispose(socket);
        return;
    }

    wprintf(L"Listening on port %d\n",boundPort);


    CkSocketW_Dispose(socket);

    }