为了更容易理解，我们举一个小例子来说明服务器与客户端之间的连接过程。
有一个饭店，饭店里有服务员，服务员用于招待客人
特别要注意的是：要记住相关函数的各个参数都是什么，什么时候返回SOCKET_ERROR,什么时候返回INVALID_SOCKET
服务器
1 #include<stdio.h> 2 #include<winsock2.h> 3 #pragma comment(lib,"ws2_32.lib"）
5 int main() 6 { 7 //初始化wsa 8 WORD wVersionRequested; 9 WSADATA wsaData; 10 int err; 11 wVersionRequested = MAKEWORD(2, 2); 12 13 err = WSAStartup(wVersionRequested, &wsaData); 14 if (err != 0) 15 { 16 17 printf("WSAStartup failed with error: %d ", err); 18 return 1; 19 } 20 21 if (LOBYTE(wsaData.wVersion) != 2 || HIBYTE(wsaData.wVersion) != 2) 22 { 23 24 printf("Could not find a usable version of Winsock.dll "); 25 WSACleanup(); 26 return 1; 27 } 28 else 29 printf("The Winsock 2.2 dll was found okay "); 30 31 SOCKET sever; 32 SOCKET waiter;//服务员用于招待客人 33 struct sockaddr_in severaddr; 34 struct sockaddr_in clientaddr;37 //创建套接字---创建饭店 38 sever=socket(AF_INET,SOCK_STREAM,IPPROTO_TCP); 39 if(sever==INVALID_SOCKET) 40 { 41 WSACleanup(); 42 return 1; 43 } 44 /*if(sever=socket(AF_INET,SOCK_STREAM,IPPROTO_TCP)==INVALID_SOCKET) 45 { 46 WSACleanup(); 47 return 1; 48 }*///这么写会导致绑定失败？？ 49 //绑定---相当于拉客，把客人拉进屋子 50 severaddr.sin_family=AF_INET; 51 severaddr.sin_port=htons(1234); 52 severaddr.sin_addr.S_un.S_addr=inet_addr("192.168.202.1"); 53 54 if(bind(sever,(const sockaddr*)&severaddr,sizeof(severaddr))==SOCKET_ERROR) 55 { 56 WSACleanup(); 57 closesocket(sever); 58 return 1; 59 }
//监听----看客人有没有要点餐的 60 if(listen(sever,4)==SOCKET_ERROR) 61 { 62 WSACleanup(); 63 return 1; 64 } 65 printf("等待连接... "); 66 int clientlen=sizeof(clientaddr);
//接收 67 waiter=accept(sever,(SOCKADDR*)&clientaddr,&clientlen);//如果有要点餐的，派一个服务员去，将客户的地址信息传给店长 68 if(waiter==INVALID_SOCKET)//第一个参数为监听套接字 69 { 70 printf("接受失败 "); 71 WSACleanup(); 72 closesocket(sever); 73 return 1; 74 } 75 while(1) 76 { 77 char recvbuf[1024]={0};//接受缓冲区 78 char sendbuf[1024]={0};//发送缓冲区 79 if(recv(waiter,recvbuf,sizeof(recvbuf),0)==SOCKET_ERROR)//服务员去负责收客户信息 80 { //waiter去收 81 printf("接受数据失败 "); 82 } 83 printf("%s ",recvbuf); 84 scanf("%s",sendbuf); 85 send(waiter,(char *)sendbuf,sizeof(sendbuf),0);//waiter去send 86 } 87 WSACleanup(); 88 closesocket(sever); 89 closesocket(waiter); 90 return 0; 91 }
客户端
1 #include<iostream> 2 #include <winsock2.h> 3 4 using namespace std; 5 #pragma comment(lib, "ws2_32.lib") 6 7 int main() 8 { 9 WORD wVersionRequested; 10 WSADATA wsaData; 11 int err; 12 wVersionRequested = MAKEWORD(2, 2); 13 14 err = WSAStartup(wVersionRequested, &wsaData); 15 if (err != 0) 16 { 17 18 printf("WSAStartup failed with error: %d ", err); 19 return 1; 20 } 21 22 if (LOBYTE(wsaData.wVersion) != 2 || HIBYTE(wsaData.wVersion) != 2) 23 { 24 25 printf("Could not find a usable version of Winsock.dll "); 26 WSACleanup(); 27 return 1; 28 } 29 else 30 printf("The Winsock 2.2 dll was found okay "); 31 32 33 //创建socket 34 SOCKET sockClient=socket(AF_INET,SOCK_STREAM ,IPPROTO_TCP ); 35 if(INVALID_SOCKET ==sockClient) 36 { 37 WSACleanup(); 38 return 1; 39 } 40 //连接服务器 41 sockaddr_in severaddr; 42 severaddr.sin_family=AF_INET; 43 severaddr.sin_port=htons(1234); 44 severaddr.sin_addr.S_un.S_addr=inet_addr("192.168.202.1"); 45 if(connect(sockClient,(const sockaddr*)&severaddr,sizeof(severaddr))==SOCKET_ERROR) 46 {//客户端去连，连接服务器地址 47 WSACleanup(); 48 closesocket(sockClient); 49 return 1; 50 } 51 while(1) 52 { 53 char szbuf[1024]={0}; 54 cin>>szbuf; 55 send(sockClient,szbuf,sizeof(szbuf),0);//客户端发送 56 int nReNum=recv(sockClient,szbuf,sizeof(szbuf),0);//客户端接收 57 if( nReNum>0) 58 { 59 cout<<szbuf<<endl; 60 } 61 } 62 WSACleanup(); 63 closesocket(sockClient); 64 return 0; 65 }