关于VC++ socket如何实现聊天全双工

关于VC++ socket如何实现聊天全双工，下面这个程序实现了单工，那位大虾给改成全双工的，（实现两方可以完全任意的发送消息，而不用你一句，对方一句那样发）多谢，急急急！！！

1、UDPchatcli端

#include <winsock2.h>

#include <stdio.h>

void main()

{

WSADATA wsaData;

WSAStartup(WINSOCK_VERSION,&wsaData);

SOCKET client = socket(AF_INET,SOCK_DGRAM,0);

struct sockaddr_in svraddr;

memset(&svraddr,0,sizeof(svraddr));

svraddr.sin_addr.S_un.S_addr = inet_addr("127.0.0.1");

svraddr.sin_family = AF_INET;

svraddr.sin_port = htons(9999);

char sendbuf[100];

char recvbuf[100];

int len = sizeof(sockaddr);

while(1)

{

gets(sendbuf);

sendto(client,sendbuf,sizeof(sendbuf)+1,0,(struct sockaddr *)&svraddr,len);

if ('q'==sendbuf[0])

{

printf("Chat end!");

break;

}

recvfrom(client,recvbuf,sizeof(recvbuf),0,(struct sockaddr *)&svraddr,&len);

printf("%s\n",recvbuf);

if ('q'==recvbuf[0])

{

printf("Chat end!");

break;

}

}

closesocket(client);

WSACleanup();

}

2、UDPchatserver端

#include <winsock2.h>

#include <stdio.h>

void main()

{

WSADATA wsaData;

WSAStartup(WINSOCK_VERSION,&wsaData);

SOCKET svr=socket(AF_INET,SOCK_DGRAM,0);

struct sockaddr_in svraddr,clientaddr;

memset(&svraddr,0,sizeof(svraddr));

svraddr.sin_addr.S_un.S_addr = inet_addr("127.0.0.1");

svraddr.sin_family = AF_INET;

svraddr.sin_port = htons(9999);

bind(svr,(struct sockaddr *)&svraddr,sizeof(svraddr));

char recvbuf[100];

char sendbuf[100];

int len = sizeof(sockaddr);

printf("This is server.");

while(1)

{

recvfrom(svr,recvbuf,sizeof(recvbuf),0,(struct sockaddr *)&clientaddr,&len);

printf("%s say %s\n",inet_ntoa(clientaddr.sin_addr),recvbuf);

if ('q'==recvbuf[0])

{

printf("Chat end!");

break;

}

printf("Please input data:\n");

gets(sendbuf);

sendto(svr,sendbuf,sizeof(sendbuf)+1,0,(struct sockaddr *)&clientaddr,len);

if ('q'==sendbuf[0])

{

printf("Chat end!");

break;

}

}

closesocket(svr);

WSACleanup();

}

你这个程序采用udp发送/接收数据，并且使用了阻塞方式的Socket，这样在读数据时会一直等到读到数据后才能执行后面的步骤，写数据时也会等到将全部数据写完才执行后面的步骤。修改这个程序首先要将创建的Socket改成异步读写的形式，然后使用select函数判断socket是否有数据可读和可以发送数据，并且udp发送的数据包不能过大，一包数据以不超过1392字节为宜。