Data to variable from file with own extension - C++ MFC

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I am developing a C++ MFC dialog based application.
I've read a couple articles about how to use my own extension for my C++ app.
I think I'll manage to edit the registry and set the assocation of the extension.

My question is:
How can I read the actual data from the file when I am double clicking on the file and my application runs. I want to set one variable with data from the file.

For example: I have a txt file with nothing more than a string containing "Hello".
When I click on the txt file and open with: MyApp.exe , the string "Hello" needs to be assigned to a CString in the C++ MFC App.

I searched for a solution, but couldn't find it.

Thanks in advance.

Michael.

Posted 20-Oct-11 3:29am

Demmers

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3 solutions

Solution 1

Use the CFile[^] class to access your file and read its contents.

Posted 20-Oct-11 3:32am

Richard MacCutchan

Solution 2

I know how to use CFile and read a file, but I cannot use this because I don't know the path of the file.
I am not running the app and then reading the file..
I want to run the file, it opens my app, because it has my own extension, and then I want to use the content of that file in my App. I don't know where the file is located on the client computer.

Do you want me to still use CFile to get what I want?

This answer is just to make sure we understand each other.

Regards, Michael.

Posted 20-Oct-11 3:47am

Demmers

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Stefan_Lang 20-Oct-11 11:17am

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Stefan_Lang · Accepted Answer · 2011-10-20T05:42:00

Once you manage to associate a specific file name extension with your application, a double-click on a file with such an extension will automatically call your application with the file name as a command line parameter. So, what you need to do is read the command line arguments.

Here is an example from http://msdn.microsoft.com/en-US/library/hwbccf8z%28v=VS.80%29.aspx[^]. I simplified it a bit for your purpose:

C++

#include <afx.h>
#include <afxwin.h>
#include <iostream>

using namespace std;

CWinApp theApp;

int main(int argc, char *argv[])
{
   if (!AfxWinInit(GetModuleHandle(NULL), NULL, GetCommandLine(), 0))
   {
      cout << "panic: MFC couldn't initialize!" << endl;
      return 1;
   }

   // see that we have a reasonable number of arguments
   if (argc != 2)
   {
      cout << "usage: " << argv[0];
      cout << " <source>" << endl;
      cout << endl;
      return 1;
   }

   // the string object to hold the file contents
   CString result;

   // constructing this file object doesn't open it
   CFile sourceFile;

   // we'll use a CFileException object to get error information
   CFileException ex;

   // open the source file for reading
   if (!sourceFile.Open(argv[1],
      CFile::modeRead | CFile::shareDenyWrite, &ex))
   {
      // complain if an error happened
      // no need to delete the ex object
      TCHAR szError[1024];
      ex.GetErrorMessage(szError, 1024);
      cout << "Couldn't open source file: ";
      cout << szError;
      return 1;
   }
   else
   {
      BYTE buffer[4096];
      DWORD dwRead;

      // Read in 4096-byte blocks, This loop ends
      // when there are no more bytes to read.
      do
      {
         dwRead = sourceFile.Read(buffer, 4096);
         result += buffer;
      }
      while (dwRead > 0);

      // Close file
      sourceFile.Close();

      // print out the total string
      cout << result << endl;
   }

   return 0;
}</source>