Check a file already exists in Save As Dialog box - c++, opencascade

I want to create a .stl file for a particular shape where each face of that shape has a different patch 开发者_运维百科name like face1,face 2 etc. I have done this by overriding the StlAPI_Writer and RWStl classes in opencascade. I have used file.Append method instead of file.Build method to do so. But I have a problem when I save the .stl file in an already existing file, it appends data to the existing one which is incorrect. I want to delete the existing data in the file and append new data face by face for a given shape.

Please help me on this.

You can use this simple function:

#include <sys/stat.h>
#include <string>

using namespace std;    

bool FileExists(string strFilename) {
  struct stat stFileInfo;
  bool blnReturn;
  int intStat;

  // Attempt to get the file attributes
  intStat = stat(strFilename.c_str(),&stFileInfo);
  if(intStat == 0) {
    // We were able to get the file attributes
    // so the file obviously exists.
    blnReturn = true;
  } else {
    // We were not able to get the file attributes.
    // This may mean that we don't have permission to
    // access the folder which contains this file. If you
    // need to do that level of checking, lookup the
    // return values of stat which will give you
    // more details on why stat failed.
    blnReturn = false;
  }

  return(blnReturn);
}

I assume you use the SaveFileDialogue class. In this case you can handle the return result of the dialogue like this:

  if ( saveFileDialog.ShowDialog() == ::DialogResult::OK )  {
     if ( FileExist(saveFileDialog.FileName) )  {
        // erase the file
     }
     // write the code using the Append function
  }

This should work, however a easier variant must be accessible if you use something else than Append (something like Write or maybe even Append but with a parameter that specifies to rewrite the file)

HTH, JP