Newbie Question: File Input and Relative Paths

This is a discussion on Newbie Question: File Input and Relative Paths within the C++ Programming forums, part of the General Programming Boards category; Hello, First of all, I apologize if this question has been answered before, but I browsed through hundreds of posts, ...

  1. #1
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    Question Newbie Question: File Input and Relative Paths

    Hello,

    First of all, I apologize if this question has been answered before, but I browsed through hundreds of posts, and couldn't find anything thus far.

    I have a program in a specified path, d:\ashiq\c++\game. All of my .cpp files are in there, as well as some plain text files I wish to input during the course of my program.

    However, I find that there is no way to open a file (for input) without putting in SOME sort of path. By default, it will check my compiler path, which is NOT what I want--I want it to use the program path. Is there a way to do this, other then manually putting in the path? Here's my IO code.

    Code:
    int showIntro()
    {
     ifstream logoStream("intro.txt");
    
     if (!logoStream)
     {
     cout << "File did not open!";
     } else {
    
      string line= "";
    
      getline(logoStream, line);
    
      while (line != "")
      {
       cout << line << "\n";
       getline(logoStream, line);
      }
     }
    
     logoStream.close();
    
     return 0;
    }
    Is it possible to get the program .exe file path, and to use relative paths? as in /data/art/temp.jpg as opposed to putting the entire path?

    Cheers,

    --Ashiq

  2. #2
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    Oops, sorry, nearly forgot:

    I'm running Dev-C++ 4.x on Windows 2000, and this is for a console application.

    --Ashiq

  3. #3
    Code Goddess Prelude's Avatar
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    >Is it possible to get the program .exe file path, and to use relative paths?
    As I understand your question, no. Such functionality would only come from a compiler option, and I've not been able to find it after a cursory search of your compiler's manual. Of course, it shouldn't be difficult to set up a path in a header file somewhere and concatenate the file name onto it when you need to open a file in a directory other than where the executable resides.
    My best code is written with the delete key.

  4. #4
    C++ Developer XSquared's Avatar
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    If you want the path of the compiled EXE file, just use argv[ 0 ].
    Naturally I didn't feel inspired enough to read all the links for you, since I already slaved away for long hours under a blistering sun pressing the search button after typing four whole words! - Quzah

    You. Fetch me my copy of the Wall Street Journal. You two, fight to the death - Stewie

  5. #5
    Code Goddess Prelude's Avatar
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    >If you want the path of the compiled EXE file, just use argv[ 0 ].
    This isn't guaranteed. argv[0] could be the full path, just the file name, a partial path, or even an empty string.
    My best code is written with the delete key.

  6. #6
    C++ Developer XSquared's Avatar
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    I thought it was always the full path to the EXE. Oh well.
    Naturally I didn't feel inspired enough to read all the links for you, since I already slaved away for long hours under a blistering sun pressing the search button after typing four whole words! - Quzah

    You. Fetch me my copy of the Wall Street Journal. You two, fight to the death - Stewie

  7. #7
    Code Goddess Prelude's Avatar
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    >I thought it was always the full path to the EXE.
    That would be nice. I say we submit a defect report about it.
    My best code is written with the delete key.

  8. #8
    C++ Developer XSquared's Avatar
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    If you're using Windows, you could try GetModuleFileName( ).

    Code:
    #include <iostream>
    #include <cstring>
    #include <windows.h>
    
    #define maxval( a, b ) ( (a) > (b) ? (a) : (b) )
    
    int main( void ) {
        
        char fileName[ MAX_PATH ];
    
        int pathLength = GetModuleFileName( GetModuleHandle( NULL ), fileName, MAX_PATH );
    
        if( !pathLength ) std::cout<<"Couldn't find path."<<std::endl;
    
        else {
    
            char *lastSlash = maxval( strrchr( fileName, '\\\' ), strrchr( fileName, '/' ) ) + 1;
    
            *lastSlash = '\0';
    
            std::cout<<"File path: "<<fileName<<std::endl;
    
        }
    
    }
    Naturally I didn't feel inspired enough to read all the links for you, since I already slaved away for long hours under a blistering sun pressing the search button after typing four whole words! - Quzah

    You. Fetch me my copy of the Wall Street Journal. You two, fight to the death - Stewie

  9. #9
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    Well...geez. What if I want to give my program to someone? ...How do other companies get around this? For surely, most programs, if not all, allow you to specify an installation path...

    Well thanks, I noticed the argv[0] thing...mine gives a full path, but I guess that's not very reliable. I'll try that anyway.

    --Ashiq

  10. #10
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    You can use the following API function. You must get it at the beginning of your program as the current directory may change during execution.

    DWORD GetCurrentDirectory(
    DWORD nBufferLength, // size, in characters, of directory buffer
    LPTSTR lpBuffer // pointer to buffer for current directory
    );


    you must use include <winbase.h>

    example
    Code:
    char buffer[255];
    GetCurrentDirectory(255, buffer);
    zMan

  11. #11
    C++ Developer XSquared's Avatar
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    GetCurrentDirectory won't necessarily return the directory that the EXE is in, though.
    Naturally I didn't feel inspired enough to read all the links for you, since I already slaved away for long hours under a blistering sun pressing the search button after typing four whole words! - Quzah

    You. Fetch me my copy of the Wall Street Journal. You two, fight to the death - Stewie

  12. #12
    Cat without Hat CornedBee's Avatar
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    There should be an option somewhere in the Dev-C++ options (maybe project options) that allows you to set the initial working directory for your app. Set it to your exe's path and the relative filenames will work.
    All the buzzt!
    CornedBee

    "There is not now, nor has there ever been, nor will there ever be, any programming language in which it is the least bit difficult to write bad code."
    - Flon's Law

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