New to C++ express, and after follow the winsock tutorial, getting countless of error.

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Asked: May 18, 20262026-05-18T10:50:47+00:00 2026-05-18T10:50:47+00:00

New to C++ express, and after follow the winsock tutorial, getting countless of error.

0

New to C++ express, and after follow the winsock tutorial, getting countless of error.
Already link the include Windows SDK 7.1 to the properties. What am I missing?

#include <winsock2.h>
#include <stdio.h>
#include <stdafx.h>

#pragma comment(lib, "Ws2_32.lib")
#ifndef WIN32_LEAN_AND_MEAN
#define WIN32_LEAN_AND_MEAN
#endif

int main(int argc, char **argv)
{
     WSADATA wsaData;

     SOCKET SendingSocket;

     // Server/receiver address

     SOCKADDR_IN          ServerAddr, ThisSenderInfo;

     // Server/receiver port to connect to

     unsigned int         Port = 7171;

     int  RetCode;

     // Be careful with the array bound, provide some checking mechanism...

     char sendbuf[1024] = "This is a test string from sender";

     int BytesSent, nlen;



     // Initialize Winsock version 2.2

     WSAStartup(MAKEWORD(2,2), &wsaData);

     printf("Client: Winsock DLL status is %s.\n", wsaData.szSystemStatus);



     // Create a new socket to make a client connection.

     // AF_INET = 2, The Internet Protocol version 4 (IPv4) address family, TCP protocol

     SendingSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);

     if(SendingSocket == INVALID_SOCKET)

     {

          printf("Client: socket() failed! Error code: %ld\n", WSAGetLastError());

          // Do the clean up

          WSACleanup();

          // Exit with error

          return -1;

     }

     else

          printf("Client: socket() is OK!\n"); 



     // Set up a SOCKADDR_IN structure that will be used to connect

     // to a listening server on port 5150. For demonstration

     // purposes, let's assume our server's IP address is 127.0.0.1 or localhost



     // IPv4

     ServerAddr.sin_family = AF_INET;

     // Port no.

     ServerAddr.sin_port = htons(Port);

     // The IP address

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



     // Make a connection to the server with socket SendingSocket.

     RetCode = connect(SendingSocket, (SOCKADDR *) &ServerAddr, sizeof(ServerAddr));

     if(RetCode != 0)

     {

          printf("Client: connect() failed! Error code: %ld\n", WSAGetLastError());

          // Close the socket

          closesocket(SendingSocket);

          // Do the clean up

          WSACleanup();

          // Exit with error

          return -1;

     }

     else

     {

          printf("Client: connect() is OK, got connected...\n");

          printf("Client: Ready for sending and/or receiving data...\n");

     }



     // At this point you can start sending or receiving data on

     // the socket SendingSocket.



     // Some info on the receiver side...

     getsockname(SendingSocket, (SOCKADDR *)&ServerAddr, (int *)sizeof(ServerAddr));

     printf("Client: Receiver IP(s) used: %s\n", inet_ntoa(ServerAddr.sin_addr));

     printf("Client: Receiver port used: %d\n", htons(ServerAddr.sin_port));



     // Sends some data to server/receiver...

     BytesSent = send(SendingSocket, sendbuf, strlen(sendbuf), 0);



     if(BytesSent == SOCKET_ERROR)

          printf("Client: send() error %ld.\n", WSAGetLastError());

     else

     {

          printf("Client: send() is OK - bytes sent: %ld\n", BytesSent);

          // Some info on this sender side...

          // Allocate the required resources

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

          nlen = sizeof(ThisSenderInfo);



          getsockname(SendingSocket, (SOCKADDR *)&ThisSenderInfo, &nlen);

          printf("Client: Sender IP(s) used: %s\n", inet_ntoa(ThisSenderInfo.sin_addr));

          printf("Client: Sender port used: %d\n", htons(ThisSenderInfo.sin_port));

          printf("Client: Those bytes represent: \"%s\"\n", sendbuf);

     }



     if( shutdown(SendingSocket, SD_SEND) != 0)

          printf("Client: Well, there is something wrong with the shutdown().

                    The error code: %ld\n", WSAGetLastError());

     else

          printf("Client: shutdown() looks OK...\n");

     // When you are finished sending and receiving data on socket SendingSocket,

     // you should close the socket using the closesocket API. We will

     // describe socket closure later in the chapter.

     if(closesocket(SendingSocket) != 0)

          printf("Client: Cannot close \"SendingSocket\" socket. Error code: %ld\n", WSAGetLastError());

     else

          printf("Client: Closing \"SendingSocket\" socket...\n");



     // When your application is finished handling the connection, call WSACleanup.

     if(WSACleanup() != 0)

          printf("Client: WSACleanup() failed!...\n");

     else

          printf("Client: WSACleanup() is OK...\n");

     return 0;

}

Error log:

    1>------ Build started: Project: ws, Configuration: Debug Win32 ------
1>Compiling...
1>ws.cpp
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(1) : warning C4627: '#include <winsock2.h>': skipped when looking for precompiled header use
1>        Add directive to 'stdafx.h' or rebuild precompiled header
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(7) : error C2065: 'WSADATA' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(7) : error C2146: syntax error : missing ';' before identifier 'wsaData'
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(7) : error C2065: 'wsaData' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(9) : error C2065: 'SOCKET' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(9) : error C2146: syntax error : missing ';' before identifier 'SendingSocket'
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(9) : error C2065: 'SendingSocket' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(13) : error C2065: 'SOCKADDR_IN' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(13) : error C2146: syntax error : missing ';' before identifier 'ServerAddr'
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(13) : error C2065: 'ServerAddr' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(13) : error C2065: 'ThisSenderInfo' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(31) : error C2065: 'wsaData' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(31) : error C3861: 'WSAStartup': identifier not found
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(31) : error C3861: 'MAKEWORD': identifier not found
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(33) : error C2065: 'wsaData' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(33) : error C2228: left of '.szSystemStatus' must have class/struct/union
1>        type is ''unknown-type''
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(41) : error C2065: 'SendingSocket' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(41) : error C2065: 'AF_INET' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(41) : error C2065: 'SOCK_STREAM' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(41) : error C2065: 'IPPROTO_TCP' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(41) : error C3861: 'socket': identifier not found
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(43) : error C2065: 'SendingSocket' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(43) : error C2065: 'INVALID_SOCKET' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(47) : error C3861: 'WSAGetLastError': identifier not found
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(51) : error C3861: 'WSACleanup': identifier not found
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(75) : error C2065: 'ServerAddr' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(75) : error C2228: left of '.sin_family' must have class/struct/union
1>        type is ''unknown-type''
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(75) : error C2065: 'AF_INET' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(79) : error C2065: 'ServerAddr' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(79) : error C2228: left of '.sin_port' must have class/struct/union
1>        type is ''unknown-type''
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(79) : error C3861: 'htons': identifier not found
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(83) : error C2065: 'ServerAddr' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(83) : error C2228: left of '.sin_addr' must have class/struct/union
1>        type is ''unknown-type''
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(83) : error C2228: left of '.s_addr' must have class/struct/union
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(83) : error C3861: 'inet_addr': identifier not found
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(89) : error C2065: 'SendingSocket' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(89) : error C2065: 'SOCKADDR' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(89) : error C2059: syntax error : ')'
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(89) : error C3861: 'connect': identifier not found
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(95) : error C3861: 'WSAGetLastError': identifier not found
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(99) : error C2065: 'SendingSocket' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(99) : error C3861: 'closesocket': identifier not found
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(103) : error C3861: 'WSACleanup': identifier not found
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(131) : error C2065: 'SendingSocket' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(131) : error C2065: 'SOCKADDR' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(131) : error C2059: syntax error : ')'
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(133) : error C2065: 'ServerAddr' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(133) : error C2228: left of '.sin_addr' must have class/struct/union
1>        type is ''unknown-type''
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(131) : error C3861: 'getsockname': identifier not found
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(133) : error C3861: 'inet_ntoa': identifier not found
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(135) : error C2065: 'ServerAddr' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(135) : error C2228: left of '.sin_port' must have class/struct/union
1>        type is ''unknown-type''
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(135) : error C3861: 'htons': identifier not found
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(141) : error C2065: 'SendingSocket' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(141) : error C3861: 'send': identifier not found
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(141) : error C3861: 'strlen': identifier not found
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(145) : error C2065: 'SOCKET_ERROR' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(147) : error C3861: 'WSAGetLastError': identifier not found
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(159) : error C2065: 'ThisSenderInfo' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(159) : error C2065: 'ThisSenderInfo' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(159) : error C2070: ''unknown-type'': illegal sizeof operand
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(159) : error C3861: 'memset': identifier not found
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(161) : error C2065: 'ThisSenderInfo' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(161) : error C2070: ''unknown-type'': illegal sizeof operand
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(165) : error C2065: 'SendingSocket' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(165) : error C2065: 'SOCKADDR' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(165) : error C2059: syntax error : ')'
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(167) : error C2065: 'ThisSenderInfo' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(167) : error C2228: left of '.sin_addr' must have class/struct/union
1>        type is ''unknown-type''
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(165) : error C3861: 'getsockname': identifier not found
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(167) : error C3861: 'inet_ntoa': identifier not found
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(169) : error C2065: 'ThisSenderInfo' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(169) : error C2228: left of '.sin_port' must have class/struct/union
1>        type is ''unknown-type''
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(169) : error C3861: 'htons': identifier not found
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(177) : error C2065: 'SendingSocket' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(177) : error C2065: 'SD_SEND' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(177) : error C3861: 'shutdown': identifier not found
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(179) : error C2001: newline in constant
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(181) : error C2146: syntax error : missing ')' before identifier 'The'
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(181) : error C2017: illegal escape sequence
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(181) : error C2001: newline in constant
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(193) : error C2065: 'SendingSocket' : undeclared identifier
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(193) : error C3861: 'closesocket': identifier not found
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(195) : error C3861: 'WSAGetLastError': identifier not found
1>c:\users\wildfire\documents\visual studio 2008\projects\ws\ws\ws.cpp(205) : error C3861: 'WSACleanup': identifier not found
1>Build log was saved at "file://c:\Users\Wildfire\Documents\Visual Studio 2008\Projects\ws\ws\Debug\BuildLog.htm"
1>ws - 84 error(s), 1 warning(s)
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

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1 Answer

Editorial Team · Answer 1 · 2026-05-18T10:50:48+00:00

Move #include "stdafx.h" to the top. It’s failing to find precompiled header file stdafx.h. It’s
the first error.

When you use precompiled headers, the header file you precompiling them through (in this case stdafx.h) should be always first line in the file (comments are ok).

Also this

#ifndef WIN32_LEAN_AND_MEAN
#define WIN32_LEAN_AND_MEAN
#endif

should go before the winsock2.h inclusion. This tells compiler not to include too many Windows SDK files to speed up compilation. Putting this after #include <winsock2.h> has no effect.

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