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File Constants
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─────Run-Time Library───────────────────────────────────────────────────────
Constant: _O_APPEND, _O_CREAT, _O_EXCL, _O_RDONLY, _O_RDWR,
_O_TRUNC, _O_WRONLY
Include: <fcntl.h>
Context: _open, _sopen, _dos_open
Summary: The integer expression formed from one or more of these
constants determines the type of reading or writing
operations permitted. It is formed by combining one or
more constants with a translation-mode constant.
See: _O_BINARY, _O_TEXT
The file constants are described below:
Constant Meaning
_O_APPEND Repositions the file pointer to the end of the file
before every write operation.
_O_CREAT Creates and opens a new file for writing; this has
no effect if the file specified by the path name
exists.
_O_EXCL Returns an error value if the file specified by the
path name exists. Only applies when used with
_O_CREAT.
_O_RDONLY Opens file for reading only; if this flag is given,
neither _O_RDWR nor _O_WRONLY can be given.
_O_RDWR Opens file for both reading and writing; if this
flag is given, neither _O_RDONLY nor _O_WRONLY can
be given.
_O_TRUNC Opens and truncates an existing file to zero length;
the file must have write permission. The contents of
the file are destroyed. If this flag is given,
_O_RDONLY cannot be given.
_O_WRONLY Opens file for writing only; if this flag is given,
neither _O_RDONLY nor _O_RDWR can be given.
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