Problems opening file

This is a discussion on Problems opening file within the C++ Programming forums, part of the General Programming Boards category; I'm having a problem opening a file and I'm thinking it's because of directories or something. I'm working on an ...

  1. #1
    myNegReal
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    Problems opening file

    I'm having a problem opening a file and I'm thinking it's because of directories or something. I'm working on an image loader and i have a file test.bmp, but whenever I call the function, it fails because fopen is returning 0 meaning it can't find the file, I know it's able to be opened, because I copied the exact same code into a function in the main cpp file and it opened just fine. I have the image loader in a folder called loaders and also in a folder called loaders in my Dev-C++ project. I'm guessing that's causing a problem? Putting the image in the loaders folder didn't work, putting ../test.bmp as the string didn't either. Any idea why it can't find the file, and how I can fix it? Thanks in advance.
    Using Dev-C++ on Windows

  2. #2
    Banned
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    fopen is C, not C++, reguardless of that posting the function
    and how you calll the function is prolly the very minimum
    of what we need you to include in order to diagnos your problem.

  3. #3
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    if your program is called with command line arguments chances are the 'current directory' isn't the program directory. if so, you can extract the application's path from the first command line arg and then just append the bitmap filename to it.

  4. #4
    myNegReal
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    Sorry for the late reply, been busy and haven't had time to check this. Here's the function, LIMAGE is a struct that contains width, height, type and a char* to hold image data.
    Code:
    LIMAGE BMPLoader::loadBMP(const char* filename) {
        struct {
            unsigned short int type;
            unsigned int filesize;
            unsigned int reserved;
            unsigned int offset;
        } header;
        struct {
            unsigned int headersize;
            unsigned int width, height;
            unsigned short int planes;
            unsigned short int bitsppx;
            unsigned int compression, imagesize, hres, vhres, numcolors, importantcols;
        } infoheader;
        char* palette = 0;
        char* imaged = 0;
        LIMAGE image = {0, 0, 0, 0};
        if (filename == 0) return image;
        FILE* file = 0;
        file = fopen(filename, "rb");
        if (file == 0) return image;
    }
    That is in loaders\bmploader.cpp. In the main CPP, in my init function I have this:
    Code:
    LIMAGE temp = BMPLoader::loadBMP("test.bmp");
    I do a check and temp contains all zeros. I did a test within in the function earlier, the filename was going through fine, for some reason fopen can't locate the file. Any ideas?
    Last edited by Ganoosh; 08-29-2005 at 12:07 AM.
    Using Dev-C++ on Windows

  5. #5
    Registered User
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    Cool

    Is test.bmp in a folder that has a space in it? Sometimes that creates problems with certain versions of Windows.

  6. #6
    myNegReal
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    Yes it is actually, but I copied the same code to the main cpp and it worked perfectly fine. For some reason the folders just mess it up or something. But I'm gonna try putting it in a spaceless-named folder and see if it works.
    Nope, didn't work.
    Using Dev-C++ on Windows

  7. #7
    Frequently Quite Prolix dwks's Avatar
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    What system are you using . . . oh yes, "Dev-C++ on Windows". Try "./filename", although that usually only causes a problem on Linux.

    Try putting the whole path in (ie, "C:\My Documents\files\filename.ext").

    [edit]
    Or rather "C:\\My Documents\\files\\filename.ext"
    [/edit]
    dwk

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