socket demonstration program under Windows

On section demonstrates  Linux  under the  socket  program, this section look at the socket program under Windows. Similarly, server.cpp for the server-side code, client to client code.

Server-side code server.cpp:

1. #include <stdio.h>
2. #include <winsock2.h>
3. #pragma comment (lib, "ws2_32.lib") // Load ws2_32.dll
4.  
5. int main () {
6. // Initialize DLL
7. WSAData wsaData;
8. WSAStartup( MAKEWORD(2, 2), &wsaData);
9.  
10. // Create a socket
11. SOCKET servSock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
12.  
13. // Bind the socket
14. sockaddr_in sockAddr;
15. memset (& sockAddr, 0, sizeof (sockAddr)); // each byte are filled with 0
16. sockAddr.sin_family = PF_INET; // use IPv4 addresses
17. sockAddr.sin_addr.s_addr = inet_addr ( "127.0.0.1"); // IP address of the specific
18. sockAddr.sin_port = htons (1234); // port
19. bind(servSock, (SOCKADDR*)&sockAddr, sizeof(SOCKADDR));
20.  
21. // enter the listening state
22. listen(servSock, 20);
23.  
24. Receiving a client request @
25. SOCKADDR clntAddr;
26. int nSize = sizeof(SOCKADDR);
27. SOCKET clntSock = accept(servSock, (SOCKADDR*)&clntAddr, &nSize);
28.  
29. // send data to the client
30. char *str = "Hello World!";
31. send(clntSock, str, strlen(str)+sizeof(char), NULL);
32.  
33. // close the socket
34. closesocket(clntSock);
35. closesocket(servSock);
36.  
37. // terminate the use of the DLL
38. WSACleanup();
39.  
40. return 0;
41. }

Client code client.cpp:

1. #include <stdio.h>
2. #include <stdlib.h>
3. #include <WinSock2.h>
4. #pragma comment (lib, "ws2_32.lib") // Load ws2_32.dll
5.  
6. int main () {
7. // Initialize DLL
8. WSAData wsaData;
9. WSAStartup(MAKEWORD(2, 2), &wsaData);
10.  
11. // Create a socket
12. SOCKET sock = socket (PF_INET, SOCK_STREAM, IPPROTO_TCP);
13.  
14. // initiate a request to the server
15. sockaddr_in sockAddr;
16. memset (& sockAddr, 0, sizeof (sockAddr)); // each byte are filled with 0
17. sockAddr.sin_family = PF_INET;
18. sockAddr.sin_addr.s_addr = inet_addr("127.0.0.1");
19. sockAddr.sin_port = htons(1234);
20. connect(sock, (SOCKADDR*)&sockAddr, sizeof(SOCKADDR));
21.  
22. // server receives the data returned
23. char szBuffer[MAXBYTE] = {0};
24. recv(sock, szBuffer, MAXBYTE, NULL);
25.  
26. // the output data received
27. printf("Message form server: %s\n", szBuffer);
28.  
29. // close the socket
30. closesocket(sock);
31.  
32. // terminate the use of DLL
33. WSACleanup();
34.  
35. system("pause");
36. return 0;
37. }

The server.cpp and client.cpp were compiled for server.exe and client.exe, run the server.exe, then run client.exe, output is:
the Message Server form:! The Hello World

socket program under Windows and Linux ideas the same, but the details are some differences:
1) socket program under Windows relies Winsock.dll or ws2_32.dll, must be loaded in advance. There are two ways to load DLL, please see: dynamic link library DLL load

2) Linux uses the concept of "file descriptor", while Windows uses "file handle" concept; Linux does not distinguish between ordinary files and socket files, and Windows distinguish ; Linux under the socket () function returns a value of type int, and for the next Windows sOCKET type, which is the handle.

3) using the following Linux read () / write () function to read and write, and the transmission and reception functions using the recv () / send () under Windows.

4) closed socket, Linux using the close () function, while Windows uses closesocket () function.