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Program cannot find an input file if the output file is saved outside of the program's directory

Posted on 2004-08-09
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Last Modified: 2010-04-01
Hello,

I have a code that takes an input file, does calculations to it and outputs it into an output file. There are 2 input files, one is asked to be provided by the user, the other one is in the ImpFiles folder in the program directory. When i run the code and save the output file in the same forder then it works fine, but when i try to save it on the desktop for example, it gives me my built in error. Heres my code:

void PropertyEstimatesElasticDlg::OnBnClickedOk()
{    
      CString inputFileFourier;
      CString temp;
      CString inputFileMaterial;
      CString outputCalculatedFile;
      GetDlgItemText(IDC_INPUT_FOURIER_ELASTIC, inputFileFourier);
       GetDlgItemText(IDC_INPUT_MATERIAL_ELASTIC, inputFileMaterial);
      GetDlgItemText(IDC_PROPERTY_OUTPUT_ELASTIC, outputCalculatedFile);

      char buffer[256];
      //Open the file where the Fourier coefficients representing the microstrucutre are
      double F[4];
      F[0]=1; //F000 is always egual to 1
      ifstream Fcoefficient (inputFileFourier);
      if (! Fcoefficient.is_open()){
            MessageBox("Error opening file.", "Fourier coefficient file.", MB_OK | MB_ICONEXCLAMATION);
            return;
      }
      Fcoefficient>>F[1]>>F[2]>>F[3];
      Fcoefficient.close();
      
      double coef[24];
      double consC[3], consS[3];
      ifstream elastic (inputFileMaterial);
      while ( elastic.eof() ){
            elastic.getline(buffer,100);
      }
      
            elastic>>consC[0]>>consC[1]>>consC[2]>>consS[0]>>consS[1]>>consS[2];

      ifstream coeff ("ImpFiles/coefficients_elastic.txt");
      if ( ! coeff.is_open())
      {
            MessageBox("Error opening file.", "coefficients_elastic file", MB_OK | MB_ICONEXCLAMATION);
            return;
      }
      while ( coeff.eof() ){
            coeff.getline(buffer,100);
      }
      for (int i=0; i<24;i++) coeff>>coef[i];

      
      
      ofstream outputfile (outputCalculatedFile);
      if (outputfile.is_open()){
//do calculation
      }
      else
      {
            MessageBox("Could not open the output file.", "Error openning file", MB_OK | MB_ICONEXCLAMATION);
            return;
      }

      outputfile.close();

      OnOK();
}

The error that I'm getting is the coefficients_elastic.txt could not be opened

Thank You
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Question by:Mad_Angel
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11 Comments
 

Author Comment

by:Mad_Angel
ID: 11756014
Maybe instead of doing this: ifstream coeff ("ImpFiles/coefficients_elastic.txt"); there's a way to make it read from ifstream coeff ("%program dir%/ImpFiles/coefficients_elastic.txt");  ?

Thanks
0
 
LVL 55

Expert Comment

by:Jaime Olivares
ID: 11756166
>    ifstream coeff ("ImpFiles/coefficients_elastic.txt");
 
You must use fully qualified path names. Something like:

c:\myappfolder\ImFiles\coefficients_elastic.txt

To achieve this, first save application folder name in a variable, and add before your filename. To obtain exe's folder use WINAPI's GetModuleFileName()
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dllproc/base/getmodulefilename.asp
0
 
LVL 86

Expert Comment

by:jkr
ID: 11756243
>>You must use fully qualified path names

That's not true. Relative paths will work also.

Where exactly does the program reside and where exactly is the input file stored. BTW, what about using

bool GetInputFileName      (      string& strName) {

      BYTE                  Filter      [ 100] = "Text (*.txt)\0*.txt\0\0";    
      char                  acBuf      [ MAX_PATH];
      OPENFILENAME      ofName;

      ZeroMemory      (      &ofName,      sizeof( OPENFILENAME));
      ZeroMemory      (      acBuf,      MAX_PATH);
   
      ofName.hwndOwner            =      NULL;
      ofName.lStructSize      =      sizeof( OPENFILENAME);
      ofName.lpstrFile        =      acBuf;
      ofName.nMaxFile         =      MAX_PATH;
      ofName.lpstrInitialDir  =      NULL;
      ofName.Flags            =      OFN_HIDEREADONLY | OFN_EXPLORER | OFN_FILEMUSTEXIST | OFN_LONGNAMES;
      ofName.lpstrDefExt      =      "txt";
      ofName.lpstrFilter      =      ( char *) Filter;
      ofName.nFilterIndex            =      1;
      ofName.lpstrTitle            =      "Choose InputFile";

      if      ( !GetOpenFileName ( &ofName))
            return ( false);

      strName = acBuf

      return ( true);
}


//...

     string strName;
     GetInputFileName(strName);
     ifstream Fcoefficient (strName.c_str());
     if (! Fcoefficient.is_open()){
         MessageBox("Error opening file.", "Fourier coefficient file.", MB_OK | MB_ICONEXCLAMATION);
         return;
    }
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LVL 55

Expert Comment

by:Jaime Olivares
ID: 11756365
Try to run you program from explorer and from inside your compiler IDE, your "current directory" won't be the same. So, if you have an "aplication directory" at the same root as your .exe file, I recommend you again to use GetModuleFileName to avoid any confussion when trying to access that folder.
That allows you to change to any user directory without lossing the "path" to your own directory.
0
 

Author Comment

by:Mad_Angel
ID: 11756417
I can't get the GetModuleFileName() to work, i tried using CString but it doesnt allow me, can you post an example please?

PS jkr, I don't want the user to provide me with coefficients_elastic.txt, i want the program to know that it's in the folder ImpFiles which is inside of the program directory.

Thanks
0
 
LVL 86

Expert Comment

by:jkr
ID: 11756473
>>i want the program to know that it's in the folder ImpFiles which is inside of the program directory.

Are you executing the application from VisualStudio? If so, try

ifstream coeff ("../ImpFiles/coefficients_elastic.txt");

since jaime_olivares is right about the IDE issue.
0
 
LVL 55

Accepted Solution

by:
Jaime Olivares earned 500 total points
ID: 11756509
Here is (tested):

      CString appDir;
      ::GetModuleFileName(NULL, appDir.GetBuffer(MAX_PATH), MAX_PATH);
      appDir.ReleaseBuffer();
      appDir = appDir.Left(appDir.ReverseFind('\\')+1);
      ::AfxMessageBox(appDir);

0
 
LVL 55

Expert Comment

by:Jaime Olivares
ID: 11756522
You can use so:

ifstream coeff (appDir+"ImpFiles/coefficients_elastic.txt");
0
 

Author Comment

by:Mad_Angel
ID: 11756538
I'm executing the program from both VisualStudio and the built file.

With ifstream coeff ("../ImpFiles/coefficients_elastic.txt"); it doesn't find the file even when i save the outpul file in the program directory where it was run from.
0
 
LVL 86

Expert Comment

by:jkr
ID: 11756597
So,

your paths are

c:\somepath\MyProject\myprog.exe
c:\somepath\MyProject\ImpFiles\coefficients_elastic.txt

?
0
 

Author Comment

by:Mad_Angel
ID: 11756785
I got it, jaime-olivares' tested code worked for me.

Thanks
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