udpclient.c

这是一个关于UDP客户端的代码

/**********************************************************************
*
*    案例二、一个最简单的UDP客户端(UdpClient.c)
*  
***********************************************************************/
#include <assert.h>
#include <stdio.h>
#include <winsock.h>

#pragma comment(lib, "WSOCK32.LIB")

#define PORT 5001
#define IPADDR "127.0.0.1"

void main()
{
	SOCKADDR_IN dst_addr;    
    WSADATA WSAData;
	SOCKET s;
	char buf[] = "hello world";

 	//该函数在Winsocket中必须调用
	if (WSAStartup(MAKEWORD(1,1), &WSAData) != 0) 
 	{
		printf("Call WSAStartup()失败!\n");
		return;
	}
   
	s = socket( AF_INET, SOCK_DGRAM, IPPROTO_UDP);
    if( s == INVALID_SOCKET) 
 	{
		printf("创建套接字失败!\n");
		return;
	}

	dst_addr.sin_port = htons(PORT);
    dst_addr.sin_addr.S_un.S_addr = inet_addr(IPADDR);
	dst_addr.sin_family = PF_INET;

	if(connect(s, (struct sockaddr FAR *)&dst_addr, sizeof(dst_addr)) == SOCKET_ERROR)
	{
		printf("连接服务器失败\n");
		return;
	}

	send(s, buf, strlen(buf), 0);
	getchar();
	closesocket(s);
	WSACleanup();
}