【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;
}