UDP聊天小程序的问题?

//////////////////////////////////////////////////////////////////////////////

#include "iostream"

#include <winsock2.h>

#include <Windows.h>

#pragma comment(lib,"ws2_32.lib")

using namespace std;

#define Const_BufLength 1024

#define Const_Port 12345



BOOL InitServerSocket(void);

BOOL InitClientSocket(void);

WSADATA wsaData;

SOCKET m_socket;

SOCKET m_client_socket;

sockaddr_in SerAdd,CliAdd;



int iLength=sizeof(CliAdd);

int retval;

char strSendMsg[Const_BufLength];

char strRecvMsg[Const_BufLength];



void ReceiveData();

void SendData();





int main()

{

	if(!InitServerSocket())

	{

		cout<<"服务套接字初始化出错，即将退出"<<endl;

		WSACleanup();

		system("pause");

		return -1;

	}



	if(!InitClientSocket())

	{

		cout<<"客户套接字初始化出错，即将退出"<<endl;

		WSACleanup();

		system("pause");

		return -1;

	}

	char ip[20];

	cout << "input ip" << endl;

	cin >> ip;

	CliAdd.sin_addr.s_addr = inet_addr(ip);



	HANDLE handle1 = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)ReceiveData, NULL, 0, NULL);

	

	while(1)

	{

		memset(strSendMsg,0,sizeof(strSendMsg));

		cout<<"回复："<<endl;

		cin >> strSendMsg;

		if(strcmp(strSendMsg,"exit")==0)

		{

			strcpy(strSendMsg,"收到客户下线的消息，我是服务器，我也下线了");

			retval=sendto(m_socket,strSendMsg,sizeof(strSendMsg),0,(SOCKADDR*)&CliAdd,sizeof(CliAdd));

			closesocket(m_socket);

			WSACleanup();

			return 0;

		}

		

		CliAdd.sin_family = AF_INET;

		retval=sendto(m_client_socket,strSendMsg,sizeof(strSendMsg),0,(SOCKADDR*)&CliAdd,sizeof(CliAdd));

		if(retval==SOCKET_ERROR)

		{

			cout<<"发送失败，错误ID为："<<WSAGetLastError()<<endl;

			break;

		}

		else if(retval==0)

		{

			break;

		}

		else

		{

			cout<<"发送成功!"<<endl;

		}

	}

	CloseHandle(handle1);

	closesocket(m_socket);

	WSACleanup();

	return 0;

}



void ReceiveData()

{

	while(1)

	{

		memset(strRecvMsg,0,sizeof(strRecvMsg));

		retval=recvfrom(m_socket,strRecvMsg,Const_BufLength,0,(SOCKADDR*)&CliAdd,&iLength);

		if(retval==SOCKET_ERROR)

		{

			cout<<"接受失败，错误ID为："<<WSAGetLastError()<<endl;

			break;

		}

		else if(retval==0)

		{

			break;

		}

		else

		{

			cout<<"IP:Port\t"<<inet_ntoa(CliAdd.sin_addr)<<":"<<ntohs(CliAdd.sin_port)<<'\t'<<strRecvMsg<<endl;

		}

	}

}





BOOL InitServerSocket(void)

{

	if(WSAStartup(MAKEWORD(2,2),&wsaData)!=0)

	{

		cout<<"加载winsock失败，错误ID为："<<WSAGetLastError()<<endl;

		exit(0);

	}

	m_socket=socket(AF_INET,SOCK_DGRAM,0);



	SerAdd.sin_family=AF_INET;

	SerAdd.sin_port=htons(Const_Port);

	SerAdd.sin_addr.S_un.S_addr=htonl(INADDR_ANY);



	int retval;

	retval=bind(m_socket,(SOCKADDR*)&SerAdd,sizeof(SOCKADDR));

	if(SOCKET_ERROR==retval)

	{

		closesocket(m_socket);

		cout<<"端口绑定失败! 错误ID为："<<WSAGetLastError()<<endl;

		return FALSE;

	}

	return TRUE;

}



BOOL InitClientSocket(void)

{

	if(WSAStartup(MAKEWORD(2,2),&wsaData)!=0)

	{

		cout<<"加载winsock失败，错误ID为："<<WSAGetLastError()<<endl;

		exit(0);

	}

	m_client_socket=socket(AF_INET,SOCK_DGRAM,0);

	if(INVALID_SOCKET==m_client_socket)

	{

		cout<<"套接字创建失败！错误ID为："<<WSAGetLastError()<<endl;

		return FALSE;

	}

	CliAdd.sin_addr.s_addr = inet_addr("127.0.0.1");

	CliAdd.sin_port = htons(Const_Port);

	return TRUE;

}