【转】C++ Socket UDP "Hello World!"

//////////////////////////////////////////////////////////////////////////
// UDPClient.cpp

#include <stdio.h>
#include <WINSOCK2.H>

#pragma comment(lib,"WS2_32.lib")
#define BUF_SIZE	64

int main(void)
{
WSADATA	wsd;
SOCKET	s;

// 初始化套接字动态库
if(WSAStartup(MAKEWORD(2,2),&wsd) != 0)
{
printf("WSAStartup failed !\n");
return 1;
}

// 创建套接字
s = socket(AF_INET,SOCK_DGRAM,0);
if(s == INVALID_SOCKET)
{
printf("socket() failed, Error Code:%d\n",WSAGetLastError());
WSACleanup();
return 1;
}

char		buf[BUF_SIZE];	// 接受数据
SOCKADDR_IN	servAddr;		// 服务器套接字地址
SOCKET		sockClient = socket(AF_INET,SOCK_DGRAM,0);
int			nRet;

ZeroMemory(buf,BUF_SIZE);
strcpy(buf,"UDP Hello World !");

// 设置服务器地址
servAddr.sin_family = AF_INET;
servAddr.sin_addr.S_un.S_addr = inet_addr("192.168.1.254");
servAddr.sin_port = htons(5000);

// 向服务器发送数据
int nServAddLen = sizeof(servAddr);
if(sendto(sockClient,buf,BUF_SIZE,0,(sockaddr *)&servAddr,nServAddLen) == SOCKET_ERROR)
{
printf("recvfrom() failed:%d\n",WSAGetLastError());
closesocket(s);
WSACleanup();
return 1;
}
nRet = recvfrom(sockClient,buf,BUF_SIZE,0,(sockaddr *)&servAddr,&nServAddLen);
if(SOCKET_ERROR == nRet)
{
printf("recvfrom failed !\n");
closesocket(s);
WSACleanup();
return -1;
}

// 打印来自服务端发送来的数据
printf("Recv From Server:%s\n",buf);
closesocket(s);
WSACleanup();
return 0;
}