TCP客户端与服务器的实现

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\n", 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\n");
25         WSACleanup();
26         return 1;
27     }
28     else
29         printf("The Winsock 2.2 dll was found okay\n");
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...\n");
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\n");
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\n");
82         }
83         printf("%s\n",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\n", 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\n");
26         WSACleanup();
27         return 1;
28     }
29     else
30         printf("The Winsock 2.2 dll was found okay\n");
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 }

原文地址：https://www.cnblogs.com/curo0119/p/8371410.html