Opening user-specified .txt file

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October 21st, 2005, 04:37 PM

HRDirector

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Opening user-specified .txt file

Is there a standard function in C++ that can open a text file for processing where that text file is determined by user input? Thanks in advance

October 21st, 2005, 04:54 PM

Scorpions4ever

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Yes. Your standard file I/O functions do this.

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October 21st, 2005, 04:54 PM

HRDirector

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Which one?

October 21st, 2005, 04:57 PM

Scorpions4ever

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The fstream object's open() method for C++ and fopen() for C. Am I missing something here?

October 21st, 2005, 05:20 PM

HRDirector

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What I mean is it how can I tell if that file exists or not, like if I needed to output

Code:

Enter file to process: "blah.txt"

ERROR: File "blah.txt" does not exist.

October 21st, 2005, 05:42 PM

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Quick N' Dirty way would be to check the return value of fopen() and make sure that it is not NULL. For C++, you could check fstream.good() after fstream.open(). Of course, failure doesn't necessarily mean that the file doesn't exist. You may not have permissions to open the file.

The alternative would be to use stat() or FindFirst() to check if the file exists.

October 21st, 2005, 11:38 PM

Dave Sinkula

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Also,

Code:

#include <iostream>
#include <fstream>
#include <cstdio>

int main()
{
   static const char filename[] = "blah.txt";
   std::ifstream file(filename);
   if ( file )
   {
      std::cout << "Opened " << filename << '\n';
   }
   else
   {
      perror(filename);
   }
   return 0;
}

/* my output
blah.txt: No such file or directory
*/

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Opening user-specified .txt file

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