fopen()                  Open a File
 
 #include   <stdio.h>
 
 FILE       *fopen(pathname,type);
 char       *pathname;                   Path name of file
 char       *type;                       Type of access permitted
 
    fopen() opens the file specified by 'pathname'.  'type' is a
    character string that specifies the type of access requested for the
    file:
 
        "r"     Open for reading only.  The file must exist.
 
        "w"     Create a new file for writing, or open an existing file
                for writing.  Use with care: If the file already exists,
                its contents will be destroyed.
 
        "a"     Append.  Open for writing at the end-of-file, or create
                for writing if the file doesn't exist.  Existing data
                cannot be overwritten in this mode.
 
        "r+"    Update. Open an existing file for reading and writing;
                the file must exist.
 
        "w+"    Open an empty file for reading and writing. Use with
                care: if the file exists, its contents will be destroyed.
 
        "a+"    Open for reading and appending; create the file if it
                doesn't exist.  All write operations take place at the
                end of the file; existing data cannot be overwritten.
 
    The following characters may be appended to the above 'types' to
    specify the translation mode for the new lines:
 
        t       Open in text (translated) mode; The CR-LF pair is
                translated to a single LF on input; LF is translated to
                CR-LF on output.
 
        b       Open in binary (untranslated) mode.  The above
                translation is suppressed.
 
    If 't' or 'b' is not specified, the translation mode is defined by
    the default mode variable '_fmode'.  '_fmode' can be set to O_BINARY,
    binary mode, or O_TEXT, text mode.  These constants are defined in
    <fcntl.h>.
 
    Returns:    A pointer to the open file.  NULL is returned on error.
 
      Notes:    Both reading and writing are allowed when using "r+",
                "w+", or "a+".
 
                Before switching between reading and writing, there must
                be an intervening fseek() or rewind().
 
  -------------------------------- Example ---------------------------------
 
    The following statements open and close a file.
 
          #include <stdio.h>
 
          FILE *in;
 
          main()
          {
              if ((in = fopen("new.dat","w+")) != NULL) {
                  .
                  .
                  .
                  fclose(in);
              }
          }

Seealso:


 fdopen() 
 freopen() 
 open() 
 fclose() 
 fcloseall()