How to fix this error: undefined reference to `__i

Question

I want make C++ program where send .txt file with information to my PC. I surch so much in internet but cant find method that works. When I uusing Dev C++ give me this errors: ...: undefined reference to __imp_InternetOpenA' ...: undefined reference to__imp_InternetConnectA' ...: undefined reference to __imp_FtpPutFileA' ...: undefined reference to__imp_HttpOpenRequestA' Here are three examples where I find, but all return this error.

  <pre>

   #include <windows.h>
   #include <wininet.h>
   #include <iostream>
   #include <stdio.h>
   #include <tchar.h>

  #pragma comment(lib,"wininet.lib")
  #define ERROR_OPEN_FILE       10
  #define ERROR_MEMORY          11
  #define ERROR_SIZE            12
  #define ERROR_INTERNET_OPEN   13
  #define ERROR_INTERNET_CONN   14
  #define ERROR_INTERNET_REQ    15
  #define ERROR_INTERNET_SEND   16

  using namespace std;

  int main()
  {
     // Local variables
     char filename[]   = "file";   //Filename to be loaded
     char filepath[]   = "d:\\a.jpg";   //Filename to be loaded
     char type[]       = "image/jpeg";
     char boundary[]  = "--BOUNDARY---";            //Header boundary
     char nameForm[]  = "formname";     //Input form name
     char iaddr[]     = "localhost";        //IP address
     char url[]       = "/http/file.php";         //URL

     char hdrs[512]={'-'};                  //Headers
     char * buffer;                   //Buffer containing file + headers
     char * content;                  //Buffer containing file
     FILE * pFile;                    //File pointer
     long lSize;                      //File size
     size_t result;                   


     // Open file
     pFile = fopen ( filepath , "rb" );
     if (pFile==NULL) 
     {
         printf("ERROR_OPEN_FILE");
         getchar();
         return ERROR_OPEN_FILE;
     }
     printf("OPEN_FILE\n");

     // obtain file size:
     fseek (pFile , 0 , SEEK_END);
     lSize = ftell (pFile);
     rewind (pFile);

     // allocate memory to contain the whole file:
     content = (char*) malloc (sizeof(char)*lSize);
     if (content == NULL) 
     {
         printf("ERROR_MEMORY");
         getchar();
         return ERROR_OPEN_FILE;
     }
     printf("MEMORY_ALLOCATED\t \"%d\" \n",&lSize);
     // copy the file into the buffer:
     result = fread (content,1,lSize,pFile);
     if (result != lSize) 
     {
         printf("ERROR_SIZE");
         getchar();
         return ERROR_OPEN_FILE;
     }
     printf("SIZE_OK\n");

     // terminate
     fclose (pFile);
     printf("FILE_CLOSE\n");
     //allocate memory to contain the whole file + HEADER
     buffer = (char*) malloc (sizeof(char)*lSize + 2048);

     //print header
     sprintf(hdrs,"Content-Type: multipart/form-data; boundary=%s",boundary);
     sprintf(buffer,"%s\r\nContent-Disposition: form-data; name=\"%s\"; filename=\"%       


----------


s\"\r\n",boundary,nameForm,filename);
     sprintf(buffer,"%sContent-Type: %s\r\n",buffer,type);
     sprintf(buffer,"%s%s",buffer,content);
     sprintf(buffer,"%s--%s--\r\n",buffer,boundary);



     //Open internet connection
     HINTERNET hSession = InternetOpen("WINDOWS",INTERNET_OPEN_TYPE_PRECONFIG, NULL, NULL, 0);
     if(hSession==NULL) 
     {
         printf("ERROR_INTERNET_OPEN");
         getchar();
         return ERROR_OPEN_FILE;
     }
     printf("INTERNET_OPENED\n");

     HINTERNET hConnect = InternetConnect(hSession, iaddr,INTERNET_DEFAULT_HTTP_PORT, NULL, NULL, INTERNET_SERVICE_HTTP, 0, 1);
     if(hConnect==NULL) 
     {
         printf("ERROR_INTERNET_CONN");
         getchar();
         return ERROR_INTERNET_CONN;
     }
     printf("INTERNET_CONNECTED\n");

     HINTERNET hRequest = HttpOpenRequest(hConnect, (const char*)"POST",_T(url),NULL, NULL, NULL,INTERNET_FLAG_RELOAD, 1);
     if(hRequest==NULL) 
      {
         printf("ERROR_INTERNET_REQ");
         getchar();

     }
     printf("INTERNET_REQ_OPEN\n");

     BOOL sent= HttpSendRequest(hRequest, hdrs, strlen(hdrs), buffer, strlen(buffer));

     if(!sent) 
     {
         printf("ERROR_INTERNET_SEND");
         getchar();
         return ERROR_INTERNET_CONN;
     }
     printf("INTERNET_SEND_OK\n");

     //close any valid internet-handles
     InternetCloseHandle(hSession);
     InternetCloseHandle(hConnect);
     InternetCloseHandle(hRequest);



     getchar();
     return 0;
  }

<pre>
  #include <winsock2.h>
  #include <wininet.h>
  #include <tchar.h>
  #include <iostream>
  #include <stdlib.h>
  #include <windows.h>

//#pragma comment(lib,"wininet.lib")

using namespace std;

int main()
{

    static TCHAR frmdata[] = "-----------------------------7d82751e2bc0858\nContent-Disposition: form-data; name=\"uploadedfile\"; filename=\"C:\test.txt\"\nContent-Type: text/plain\n\nfile contents  here\n-----------------------------7d82751e2bc0858--"; 
    static TCHAR hdrs[] = "Content-Type: multipart/form-data; boundary=---------------------------7d82751e2bc0858"; 

    HINTERNET hSession = InternetOpen("MyAgent",INTERNET_OPEN_TYPE_PRECONFIG, NULL, NULL, 0);
     if(hSession==NULL)
    {
     cout<<"Error: InternetOpen";  
    }


    HINTERNET hConnect = InternetConnect(hSession, _T("localhost"),INTERNET_DEFAULT_HTTP_PORT, NULL, NULL, INTERNET_SERVICE_HTTP, 0, 1);
     if(hConnect==NULL)
    {
     cout<<"Error: InternetConnect";  
    }

    HINTERNET hRequest = HttpOpenRequest(hConnect, (const char*)"POST",_T("upload.php"), NULL, NULL, (const char**)"*/*\0", 0, 1);
    if(hRequest==NULL)
    {
     cout<<"Error: HttpOpenRequest";  
    }

    BOOL sent= HttpSendRequest(hRequest, hdrs, strlen(hdrs), frmdata, strlen(frmdata));
    if(!sent)
    {
     cout<<"Error: HttpSendRequest";
     }

    //close any valid internet-handles
    InternetCloseHandle(hSession);
    InternetCloseHandle(hConnect);
    InternetCloseHandle(hRequest);

    return 0;
}

    #include <windows.h>
      #include <wininet.h>
      #include <stdio.h>
      #include <iostream>


      #define ERROR_OPEN_FILE       10
      #define ERROR_MEMORY          11
      #define ERROR_SIZE            12
      #define ERROR_INTERNET_OPEN   13
      #define ERROR_INTERNET_CONN   14
      #define ERROR_INTERNET_REQ    15
      #define ERROR_INTERNET_SEND   16

      using namespace std;

      int main()
      {
         // Local variables
         static char filename[]   = "test.txt";   //Filename to be loaded
         static char type[]       = "image/jpg";
         static char boundary[]  = "pippo";            //Header boundary
         static char nameForm[]  = "uploadedfile";     //Input form name
         static char iaddr[]     = "localhost";        //IP address
         static char url[]       = "test.php";         //URL

         char hdrs[255];                  //Headers
         char * buffer;                   //Buffer containing file + headers
         char * content;                  //Buffer containing file
         FILE * pFile;                    //File pointer
         long lSize;                      //File size
         size_t result;                   


         // Open file
         pFile = fopen ( filename , "rb" );
         if (pFile==NULL) return ERROR_OPEN_FILE;

         // obtain file size:
         fseek (pFile , 0 , SEEK_END);
         lSize = ftell (pFile);
         rewind (pFile);

         // allocate memory to contain the whole file:
         content = (char*) malloc (sizeof(char)*lSize);
         if (content == NULL) return ERROR_MEMORY;

         // copy the file into the buffer:
         result = fread (content,1,lSize,pFile);
         if (result != lSize) return ERROR_SIZE;

         // terminate
         fclose (pFile);

         //allocate memory to contain the whole file + HEADER
         buffer = (char*) malloc (sizeof(char)*lSize + 2048);

         //print header
         sprintf(hdrs,"Content-Type: multipart/form-data; boundary=%s",boundary);
         sprintf(buffer,"--%s\r\nContent-Disposition: form-data; name=\"%s\"; filename=\"%s\"\r\n",boundary,nameForm,filename);
         sprintf(buffer,"%sContent-Type: %s\r\n\r\n",buffer,type);
         sprintf(buffer,"%s%s\r\n",buffer,content);
         sprintf(buffer,"%s--%s--\r\n",buffer,boundary);

         //Open internet connection
         HINTERNET hSession = InternetOpen("WinSock",INTERNET_OPEN_TYPE_PRECONFIG, NULL, NULL, 0);
         if(hSession==NULL) return ERROR_INTERNET_OPEN;

         HINTERNET hConnect = InternetConnect(hSession, iaddr,INTERNET_DEFAULT_HTTP_PORT, NULL, NULL, INTERNET_SERVICE_HTTP, 0, 1);
         if(hConnect==NULL) return ERROR_INTERNET_CONN;

         HINTERNET hRequest = HttpOpenRequest(hConnect, (const char*)"POST",url, NULL, NULL, (const char**)"*/*\0", 0, 1);
         if(hRequest==NULL) return ERROR_INTERNET_REQ;

         BOOL sent= HttpSendRequest(hRequest, hdrs, strlen(hdrs), buffer, strlen(buffer));
         if(!sent) return ERROR_INTERNET_SEND;

         //close any valid internet-handles
         InternetCloseHandle(hSession);
         InternetCloseHandle(hConnect);
         InternetCloseHandle(hRequest);

         return 0;
      }

 </pre>

Answer 1

I had many errors like this on my first C++ program. It is a problem with linking against the WinINet library. If you are using MinGW add "-lwininet" (without quotes) to the additional commandling arguments and it should be fixed. I don't know what to to do if you use VC++. Also, make sure the location of the WinINet library is in the linker's search paths.

Answer 2

With CMake you simply need

target_link_libraries( MY_TARGET
                       ws2_32)