UDP01
#include <windows.h>
#include <winsock.h>
#pragma comment(lib,"ws2_32.lib")

HINSTANCE hInst;
LRESULT CALLBACK WndProc(HWND,UINT,WPARAM,LPARAM);
int APIENTRY WinMain(HINSTANCE hI,HINSTANCE hP,LPSTR lp,int nC)
{
  MSG msg;
  HWND hWnd;
  hInst = hI;
  WNDCLASS wc;
  memset(&wc,0,sizeof(WNDCLASS));
  wc.lpfnWndProc = (WNDPROC)WndProc;
  wc.hInstance = hI;
  wc.hIcon = LoadIcon(NULL,IDI_APPLICATION);
  wc.hbrBackground = (HBRUSH)COLOR_WINDOW;
  wc.lpszClassName = "W1";
  RegisterClass(&wc);
  hWnd = CreateWindowEx(WS_EX_PALETTEWINDOW,"W1","UDP程序2 端口号：8000",
                        WS_OVERLAPPEDWINDOW,100,100,200,100,NULL,NULL,
                        hI,NULL );
  if(!hWnd) return FALSE;
  ShowWindow(hWnd,nC);

  while(GetMessage(&msg,NULL,0,0))
  {
    TranslateMessage(&msg);
    DispatchMessage(&msg);
  }
  return msg.wParam;
  
}


////////////////////////////////////////////////////
//定义winsock API需要的量
WSADATA ws;
SOCKET s1,s2;
struct sockaddr_in Cs1A,Cs2A;
char sendBuf[200];
char recvBuf[200];
int len;
#define Cs1Port 6000
#define Cs2Port 8000
#define Cs1IP "127.0.0.1"
#define Cs2IP "127.0.0.1"
//////////////////////////////////////////////////


LRESULT CALLBACK WndProc(HWND hW,UINT msg,WPARAM wP,LPARAM IP)
{
  switch(msg)
  {
     case WM_DESTROY://关闭程序触发事件
                     WSAAsyncSelect(s1,hW,0,0);//向Windows注销socket触发事件
                     closesocket(s1);//释放连接
                     WSACleanup();//卸载winsock库
                     PostQuitMessage(0);
                     break;
     case WM_CREATE://初始化触发事件
                     WSAStartup(0x0202,&ws);
                     s1 = socket(AF_INET,SOCK_DGRAM,0);
                     //本地
                     Cs1A.sin_family = AF_INET;
                     Cs1A.sin_port = htons(Cs1Port);
                     Cs1A.sin_addr.s_addr = inet_addr(Cs1IP);
                     len = bind(s1,(struct sockaddr *)&Cs1A,sizeof(Cs1A));
                     //远程
                     Cs2A.sin_family = AF_INET;
                     Cs2A.sin_port = htons(Cs2Port);
                     Cs2A.sin_addr.s_addr = inet_addr(Cs2IP);
                     WSAAsyncSelect(s1,hW,WM_USER+1,FD_READ);//向Windows注册网络事件
                    
                     break;

     case WM_USER+1://socket触发事件
                    switch(LOWORD(IP))
                    {
                      case FD_READ: len = recv(s1,recvBuf,sizeof(recvBuf),0);
                                    recvBuf[len] = 0;
                                    MessageBox(0,recvBuf,"UDP程序2从UDP程序1收到的数据",0);
                                    break;
                    }
                    break;
     case WM_LBUTTONDOWN://点击鼠标左键
                       wsprintf(sendBuf,"Hello,UDO程序1！");
                       len = sizeof(Cs2A);
                       sendto(s1,sendBuf,strlen(sendBuf),0,(struct sockaddr *)&Cs2A,len);
                       break;
  }
  return DefWindowProc(hW,msg,wP,IP);
}


UDP2
#include <windows.h>
#include <winsock.h>
#pragma comment(lib,"ws2_32.lib")

HINSTANCE hInst;
LRESULT CALLBACK WndProc(HWND,UINT,WPARAM,LPARAM);
int APIENTRY WinMain(HINSTANCE hI,HINSTANCE hP,LPSTR lp,int nC)
{
  MSG msg;
  HWND hWnd;
  hInst = hI;
  WNDCLASS wc;
  memset(&wc,0,sizeof(WNDCLASS));
  wc.lpfnWndProc = (WNDPROC)WndProc;
  wc.hInstance = hI;
  wc.hIcon = LoadIcon(NULL,IDI_APPLICATION);
  wc.hbrBackground = (HBRUSH)COLOR_WINDOW;
  wc.lpszClassName = "W1";
  RegisterClass(&wc);
  hWnd = CreateWindowEx(WS_EX_PALETTEWINDOW,"W1","UDP程序1 端口号：6000",
                        WS_OVERLAPPEDWINDOW,400,200,200,100,NULL,NULL,
                        hI,NULL );
  if(!hWnd) return FALSE;
  ShowWindow(hWnd,nC);

  while(GetMessage(&msg,NULL,0,0))
  {
    TranslateMessage(&msg);
    DispatchMessage(&msg);
  }
  return msg.wParam;
  
}


////////////////////////////////////////////////////
//定义winsock API需要的量
WSADATA ws;
SOCKET s1,s2;
struct sockaddr_in Cs1A,Cs2A;
char sendBuf[200];
char recvBuf[200];
int len;
#define Cs1Port 8000
#define Cs2Port 6000
#define Cs1IP "127.0.0.1"
#define Cs2IP "127.0.0.1"
//////////////////////////////////////////////////


LRESULT CALLBACK WndProc(HWND hW,UINT msg,WPARAM wP,LPARAM IP)
{
  switch(msg)
  {
     case WM_DESTROY://关闭程序触发事件
                     WSAAsyncSelect(s1,hW,0,0);//向Windows注销socket触发事件
                     closesocket(s1);//释放连接
                     WSACleanup();//卸载winsock库
                     PostQuitMessage(0);
                     break;
     case WM_CREATE://初始化触发事件
                     WSAStartup(0x0202,&ws);
                     s1 = socket(AF_INET,SOCK_DGRAM,0);
                     //本地
                     Cs1A.sin_family = AF_INET;
                     Cs1A.sin_port = htons(Cs1Port);
                     Cs1A.sin_addr.s_addr = inet_addr(Cs1IP);
                     len = bind(s1,(struct sockaddr *)&Cs1A,sizeof(Cs1A));
                     //远程
                     Cs2A.sin_family = AF_INET;
                     Cs2A.sin_port = htons(Cs2Port);
                     Cs2A.sin_addr.s_addr = inet_addr(Cs2IP);
                     WSAAsyncSelect(s1,hW,WM_USER+1,FD_READ);//向Windows注册网络事件
                    
                     break;

     case WM_USER+1://socket触发事件
                    switch(LOWORD(IP))
                    {
                      case FD_READ: len = recv(s1,recvBuf,sizeof(recvBuf),0);
                                    recvBuf[len] = 0;
                                    MessageBox(0,recvBuf,"UDP程序1从UDP程序2收到的数据",0);
                                    break;
                    }
                    break;
     case WM_LBUTTONDOWN://点击鼠标左键
                       wsprintf(sendBuf,"Hello,UDO程序2！");
                       len = sizeof(Cs2A);
                       sendto(s1,sendBuf,strlen(sendBuf),0,(struct sockaddr *)&Cs2A,len);
                       break;
  }
  return DefWindowProc(hW,msg,wP,IP);
}