◄ifstream►                                    ◄Up► ◄Contents► ◄Index► ◄Back►
──The Microsoft iostream Classes────────────────────────────────────────────
 
  ifstream();
  ifstream( const char* szName, int nMode = ios::in,
            int nProt = filebuf::openprot );
  ifstream( filedesc fd );
  ifstream( filedesc fd, char* pch, int nLength );
 
  Parameter   Description
 
  <szName>    The name of the file to be opened during construction.
 
  <nMode>     An integer that contains mode bits defined as ios
              enumerators that can be combined with the bitwise-OR (|)
              operator:
 
              Value           Meaning
 
              ios::in         The file is opened for input (default).
 
              ios::nocreate   If the file does not already exist, the
                              function fails.
 
              ios::binary     Opens the file in binary mode (the default
                              is text mode).
 
              Note that the ios::nocreate flag is necessary if you intend
              to test for the file's existence (the usual case).
 
  <nProt>     The file protection specification; defaults to the static
              integer filebuf::openprot that is equivalent to
              filebuf::sh_compat. The possible <nProt> values are as
              follows:
 
              Value                Meaning
 
              filebuf::sh_compat   Compatibility share mode.
 
              filebuf::sh_none     Exclusive mode──no sharing.
 
              filebuf::sh_read     Read sharing allowed.
 
              filebuf::sh_write    Write sharing allowed.
 
              The filebuf::sh_read and filebuf::sh_write modes can be
              combined with the logical OR (|) operator.
 
  <fd>        A file descriptor as returned by a call to the run-time
              function  _open or _sopen; filedesc is a typedef equivalent
              to int.
 
  <pch>       Pointer to a previously allocated reserve area of length
              <nLength>. A NULL value (or <nLength> = 0) indicates that
              the stream will be unbuffered.
 
  <nLength>   The length (in bytes) of the reserve area (0 = unbuffered).
 
  Remarks
 
  The four ifstream constructors are described as follows:
 
  Constructor                         Description
 
  ifstream()                          Constructs an ifstream object
                                      without opening a file.
 
  ifstream( const char*, int, int )   Contructs an ifstream object,
                                      opening the specified file.
 
  ifstream( filedesc )                Constructs an ifstream object that
                                      is attached to an open file.
 
  ifstream( filedesc, char*, int )    Constructs an ifstream object that
                                      is associated with a filebuf object.
                                      The filebuf object is attached to an
                                      open file and to a specified reserve
                                      area.
 
  All ifstream constructors construct a filebuf object. The first three
  use an internally allocated reserve area, but the fourth uses a
  user-allocated area.
 
 
                                     -♦-