File constants
Syntax
#include <fcntl.h>
Remarks
The integer expression formed from one or more of these constants determines the type of reading or writing operations permitted. It's formed by combining one or more constants with a translation-mode constant.
The file constants are as follows:
| Constant | Description |
|---|---|
_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; the constant has no effect if the file specified by filename exists. |
_O_EXCL |
Returns an error value if the file specified by filename exists. Only applies when used with _O_CREAT. |
_O_RDONLY |
Opens file for reading only; if this flag is given, _O_RDWR and _O_WRONLY can't be given. |
_O_RDWR |
Opens file for both reading and writing; if this flag is given, _O_RDONLY and _O_WRONLY can't 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, you can't specify _O_RDONLY. |
_O_WRONLY |
Opens file for writing only; if this flag is given, _O_RDONLY and _O_RDWR can't be given. |