Platform independent paths

This is a discussion on Platform independent paths within the C Programming forums, part of the General Programming Boards category; G'day! Okay, I'm writting a little portable application and I want to separate the data from the executable. What's the ...

  1. #1
    Woof, woof! zacs7's Avatar
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    Platform independent paths

    G'day!

    Okay, I'm writting a little portable application and I want to separate the data from the executable. What's the best way to generate/use these paths at runtime? So far I'm using the pre-processor but that's a bit ugly.

    ie,

    Code:
    fp = fopen(BASE_PATH "fonts" PATH_SEP "test.fnt", "rb");
    And BASE_PATH is generated by my makefile. Ie, on Windows it might be "C:\Program Files\xxx\" or "/usr/share/xxx/" on Linux.

    Or generating them at runtime, but then I need to free them if I use the heap!

    Thanks!
    Zac

    PS: This is the board of best fit, General didn't make sense. Nor did the Linux or Windows boards :-)
    Last edited by zacs7; 11-21-2008 at 09:10 PM.

  2. #2
    Just Lurking Dave_Sinkula's Avatar
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    How about...?
    Code:
    fp = fopen(BASE_PATH "fonts/test.fnt", "rb");
    7. It is easier to write an incorrect program than understand a correct one.
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  3. #3
    and the hat of sweating
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    You don't need to. The Windows API handles '/' and converts it to '\' for you. Give it a try.
    But of course the command line doesn't handle '/', so if you're using the system() call you'd need to make the paths correct.
    "I am probably the laziest programmer on the planet, a fact with which anyone who has ever seen my code will agree." - esbo, 11/15/2008

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  4. #4
    Woof, woof! zacs7's Avatar
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    Hmm thanks :-)

  5. #5
    Kernel hacker
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    The other solution (should you be in a situation where / isn't translated in windows, or you are moving a Windows app to Linux), is to form the path as usual, and then replace fopen() with a macro like this:
    Code:
    // 0myfopen.h or osdep.h (as you are bound to have other functions that are specific to a partciular system)
    #define fopen(x, y) myfopen(x, y)
    FILE *myfopen(const char *fname, const char *mode);
    
    
    .... 
    
    // myfopen.c or linux/win/macosdep.c
    #undef fopen()
    FILE *myfopen(const char *fname, const char *mode)
    {
         FILE *f;
         char *tmpname = convert(fname);
         if (tmpname)
         {
             f = fopen(tmpname, mode);
             free(tmpname);
             return f;
         }
         // Error message??
         return NULL;
    }
    Convert would allocate a new copy of the string and translate as appropriate.

    --
    Mats
    Compilers can produce warnings - make the compiler programmers happy: Use them!
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  6. #6
    Woof, woof! zacs7's Avatar
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    Thanks matsp . I'll have to use that anyway when I do runtime detection of a writeable path ie a home directory or "My Documents".

  7. #7
    C++まいる!Cをこわせ!
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    I believe Windows API translates '/' to '\' due to backwards compatibility, but I don't think Microsoft will rip that out anytime soon, so I think you're safe
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    You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.

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