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May 3rd, 2007

Sending a dos environment variable to fstream instance

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Hi all,
I apologize if this is somewhere on here. I've looked some and I can't find it here or anywhere on the internet. With all the bright minds on this board, someone's bound to have an idea...

What I would like to do is open a file using the fstream class, but the pathname is going to be computer independent. In other words, I would like to call something of the following sort:

c++ Syntax (Toggle Plain Text)
ifstream file("%APPDATA%\\Folder\\file.txt");
//do stuff...
ifstream file("%APPDATA%\\Folder\\file.txt");
//do stuff...

Unfortunately, whenever I try using %APPDATA% or %HOMEPATH%, it seems to be sending something else to the ifstream's open method.

Any ideas/suggestions?
I appreciate any and all help - Thanks!

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Coach_Nate

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May 3rd, 2007

Re: Sending a dos environment variable to fstream instance

Environment variables aren't expanded in string literals. You need to call something like getenv to get the value:

C++ Syntax (Toggle Plain Text)
#include <cstdlib>
 
//...
 
const char *appdata = std::getenv ( "APPDATA" );
 
if ( appdata != 0 ) {
  std::string path = appdata;
 
  path += "\\Folder\\file.txt";
 
  std::ifstream file ( path.c_str() );
 
  //...
}
#include <cstdlib>

//...

const char *appdata = std::getenv ( "APPDATA" );

if ( appdata != 0 ) {
  std::string path = appdata;

  path += "\\Folder\\file.txt";

  std::ifstream file ( path.c_str() );

  //...
}

Last edited by Narue; May 3rd, 2007 at 1:25 pm.

Narue

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May 3rd, 2007

Re: Sending a dos environment variable to fstream instance

OH YEA! Thanks, Narue. I remember seeing the getenv function used somewhere else, but it's been a little while since I've done any actual c/c++ coding. Lately it's been mostly Java. But hey, Thanks again!

Coach_Nate

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May 3rd, 2007

Re: Sending a dos environment variable to fstream instance

>Lately it's been mostly Java.
I'm sorry.

Narue

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