UDP-based communication

XX: the drifting 100 ~ _~ {2014/10/03 10: 57}

UDP is a non-connection-oriented sock_dgram service that provides connectionless services. Data packets are sent in the form of independent packets. No guarantee is provided. data can be lost or duplicated.

The difference between UDP server and client is relatively vague. You only need to call sendto and recvfrom to send and receive data to the specified address.

1. server side:

// Udpclient. CPP: defines the entry point for the application. // # include "stdafx. H "# include" tchar. H "# pragma comment (Lib," wsock32.lib ") # include <stdio. h ># include <winsock2.h> bool initwinsock (); // The Winsock service initializes void main () {socket socket1; initwinsock (); struct sockaddr_in local; struct sockaddr_in from; int err; int fromlean = sizeof (from); Local. sin_family = af_inet; local. sin_port = htons (1234); // listener port local. sin_a DDR. s_un.s_addr = inaddr_any; // socket1 = socket (af_inet, sock_dgram, 0); BIND (socket1, (sockaddr *) & Local, sizeof local); While (true) {char buffer [1024] = "\ 0"; printf ("waiting for message from others \ n"); err = recvfrom (socket1, buffer, sizeof (buffer), 0, (sockaddr *) & from, & fromlean); If (Err! = Socket_error) {printf ("received from % s -- % s \ n", inet_ntoa (from. sin_addr), buffer); // send message sendto (socket1, buffer, sizeof buffer, 0, (sockaddr *) & from, fromlean) to the client;} Sleep (500 );} closesocket (socket1);} bool initwinsock () {int error; Word version; wsadata WSA; version = makeword (2, 2); error = wsastartup (version, & WSA ); if (error! = 0) {return false;} else {If (lobyte (WSA. wversion )! = 2 | hibyte (WSA. whighversion )! = 2) {wsacleanup (); Return false ;}} return true ;}

2. Client

// Udpclient. CPP: defines the entry point for the application. // # include "stdafx. H "# include" tchar. H "# pragma comment (Lib," wsock32.lib ") # include <stdio. h ># include <winsock2.h> bool initwinsock (); // The Winsock service initializes void main () {socket socket1; initwinsock (); struct sockaddr_in server; int err; int lean = sizeof (server); server. sin_family = af_inet; server. sin_port = htons (1234); // The listening port of the server is 1234server. sin_addr.s_un.s_ad Dr = inet_addr ("192.168.1.18"); // set it to the local address socket1 = socket (af_inet, sock_dgram, 0); While (true) {char buffer [1024] = "\ 0"; printf ("input message \ n"); scanf ("% s", buffer); If (strcmp (buffer, "bye") = 0) {break;} err = sendto (socket1, buffer, sizeof (buffer), 0, (sockaddr *) & server, lean ); if (Err! = Socket_error) {err = recvfrom (socket1, buffer, sizeof (buffer), 0, (sockaddr *) & server, & lean); If (Err! = Socket_error) {printf ("receive from server: % s \ n", buffer) ;}} closesocket (socket1);} bool initwinsock () {int error; Word version; wsadata WSA; version = makeword (2, 2); error = wsastartup (version, & WSA); If (error! = 0) {return false;} else {If (lobyte (WSA. wversion )! = 2 | hibyte (WSA. whighversion )! = 2) {wsacleanup (); Return false ;}} return true ;}

Start the client and server to view the running effect:

There are still a lot of problems with the program. Please modify it slowly!

 

UDP-based communication