多线程UDP通信（可以自己给自己发）

#pragma warning(disable:4996)
#include //多线程编程
using namespace std;
#include 
#include  //_beginthread需要的头文件 即多线程
#pragma comment(lib,"ws2_32.lib")
#define _WINSOCK_DEPRECATED_NO_WARNINGS 
	//WORD wVer = 0x0302; //2.3版本
	//WORD wVer = 0x0300; //0.3
	//WORD wVer = 0x0202; //2.2版本
const unsigned short PORT = 8888;//端口
SOCKET sock;
void RecvMain(void * p) 
{
	char s[2048]; 
	sockaddr_in sfrom = {0};
	int slen = sizeof(sfrom);//in out
	SOCKET sock = (SOCKET)p;
	int n = 0;
	while ((n = recvfrom(sock, s, sizeof(s), 0, (sockaddr*)&sfrom, &slen)) > 0)
	{
		s[n] = '\0';
		//cout << WSAGetLastError() << endl;
		cout << endl << inet_ntoa(sfrom.sin_addr) << "-" << htons(sfrom.sin_port) << ": " << s << endl;
	}
}
int main(int argc, char* argv[]) 
{
	WSADATA wd;
	SOCKET sock;
	int n = WSAStartup(0x0202,&wd);//0代表成功，否则是直接返回错误码
	sock = socket(AF_INET,SOCK_DGRAM,0);
	if (INVALID_SOCKET == sock) 
	{
		cout << "socket函数错误：" << WSAGetLastError << endl;
		return -1;
	}
	struct sockaddr_in sa = {AF_INET,htons(PORT)};
	//sa.sin_addr.Sun.S_addr = inet_addr("192.168.1.1");
	n = bind(sock, (sockaddr*)&sa, sizeof(sa));
	//Address Family 地址族
	if (n == SOCKET_ERROR)
		cout << "bind函数错误：" << WSAGetLastError() << endl;
	else
		cout << "端口发布成功：" << PORT << endl;
	_beginthread(RecvMain,1024*1024,(void*)sock);//多线程，再次调用int main主函数 实现两个线程

	char s[2048];
	char sIP[20];
	while (true) 
	{
		cout << "请输入对方的IP: ";
		cin >> sIP; 
		cin.get();
		cout << "请输入要发送的内容：";
		fflush(stdin);
		cin.getline(s,2047);
		sa.sin_addr.S_un.S_addr = inet_addr(sIP);
		sa.sin_port = htons(PORT);
		sendto(sock, s, strlen(s), 0, (sockaddr*)&sa, sizeof(sa));
		Sleep(16); //延迟16毫秒
	}
	cin.get();
	return 0;
}