fopen filename parameter

This is a discussion on fopen filename parameter within the C Programming forums, part of the General Programming Boards category; I'm not sure if this question has been asked already recently anyway (at least I'm having trouble finding a topic ...

  1. #1
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    fopen filename parameter

    I'm not sure if this question has been asked already recently anyway (at least I'm having trouble finding a topic similar to my question). For the filename parameter of fopen function, if I'm not specifying a full filepath, does the program assume that the filename is in the same directory as itself?

  2. #2
    Deathray Engineer MacGyver's Avatar
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    Concept of a working directory. Most of the time, yes, the working dir will be the same dir the exe is located in, but not necessarily.

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    How would I set the working directory then (if i'm not using it in an IDE)? Would it be safe to explicitly state the path in filename?

  4. #4
    Deathray Engineer MacGyver's Avatar
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    If you're on Unix or the like, you could set it via chdir().

    Yes, it would be safe to set it via the filename, however, you could just assume a relative location to the working directory.

  5. #5
    HelpingYouHelpUsHelpUsAll
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    It looks like it: http://www.cplusplus.com/reference/c...dio/fgets.html It doesn't take long to try it out though. E.g. the following works for me when "myfile.txt is in the same directory as the path for cmd. Otherwise it can't find the program, so when given a relitive path, it serces in the current directory. Try out other things, like putting the file to open in the system root and c if it finds it. Note opening with write access creates the file if non-existant:
    Code:
    /* fopen example from site above*/
    #include <stdio.h>
    int main ()
    {
      FILE * pFile;
       char mystring [100];
      pFile = fopen ("myfile.txt","r");
      if (pFile == NULL) perror ("Error opening file");
      else
      {
         fgets (mystring , 100 , pFile);
         puts (mystring);
         fclose (pFile);
      }
      return 0;
    }
    long time no C; //seige
    You miss 100% of the people you don't C;
    Code:
    if (language != LANG_C && language != LANG_CPP)
        drown(language);

  6. #6
    and the hat of wrongness Salem's Avatar
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    The working directory is normally the directory your command line "shell" is currently in when the program is invoked.

    Windows on the other hand seems to make a complete mess of it.
    If you double-click on an exe, it's one place
    If you drag/drop a file onto it, it's another place
    and so on.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
    I support http://www.ukip.org/ as the first necessary step to a free Europe.

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