Windows File I/O vs. C Run-time File I/O
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The following functions are provided by the Microsoft C Run-time Library(CRT) and the Windows API to create a file:
Return Type API or Function Category -------------------------------------------- HFILE OpenFile Windows API HFILE _lopen/_lcreat Windows API int _open/_creat CRT FILE * fopen CRTThese return types (HFILE, int, and FILE *) are not compatible, so they cannot be used in a function which is expecting the other type. The HFILEs arehandles to operating system files (MS-DOS file handles), the ints are CRTfile handles, and the FILE *s are pointers to structures which represent aCRT stream.
For files opened with OpenFile(), _lopen, and _lcreat, the common filemanipuluation routines that you should use are:
_lcloseFor files opened with _open() and _creat(), the common file manipulationroutines that you should use are:
_closeFor files opened with fopen, the common file manipulation routines that youshould use are:
fcloseFor other input and output functions, please check the documentation forinformation on whether they are intended for use with MS-DOS handles(HFILE), streams (FILE *), or low-level I/O (int).
An application should use the OpenFile() API any time an MS-DOS file handleis required.
The open functions do not necessarily open a file in binary raw mode; theapplication is required to set the binary attribute explicitly. TheOpenFile() function automatically performs this step.
If the filename parameter specifies only a filename and extension, the openfunctions search for a matching file only in the current directory.
In Windows, the OpenFile() API creates an MS-DOS file handle through whichan application can access Windows-specific files. OpenFile() initiallyopens the file in binary raw mode by performing an MS-DOS Interrupt 21hFunction 3Dh. If the lpFileName parameter specifies only a filename and anextension, OpenFile() searches for a matching file in the followingdirectories:
- The current directory.
- The Windows directory. The GetWindowsDirectory() API returns the path to this directory.
- The Windows system directory . The GetSystemDirectory() API returns the path to this directory.
- The directories listed in the PATH environment variable.
Article ID: 11988 - Last Review: 12/04/2015 08:54:23 - Revision: 3.0
Microsoft Windows Software Development Kit 3.0, Microsoft Windows Software Development Kit 3.1
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