Debugging-Use of setsockopt

Target: Create a socket, use setsockopt to set its attribute to the broadcast type, and

This broadcast socket sends a broadcast to the System

Problem: The creation (socket), setting (setsockopt), and binding (BIND) are successful, that is, the sendto call fails.

Cause: The optval parameter of setsockopt () is not initialized and should be as follows:

Int optval = 1; (type conversion is required when calling ---Char *)

Or

Char optval = 1;

Setsockopt

TheSetsockoptFunction sets a socket option.

int setsockopt(  SOCKET s,  int level,  int optname,  const char* optval,  int optlen);

Parameters

S

[In] descriptor identifying a socket.

Level

[In] level at which the option is defined; The supported LevelS include Sol_socketAnd ipproto_tcp. See Windows Sockets 2 protocol-Specific Annex for more information on protocol-specific levels.

Optname

[In] socket option for which the value is to be set.

Optval

[In] pointer to the buffer in which the value for the requested option is specified.

Optlen

[In] size of OptvalBuffer, in bytes.

Return values

If no error occurs,SetsockoptReturns zero. Otherwise, a value of socket_error is returned, and a specific error code can be retrieved by callingWsagetlasterror.