The file-handling routines let you create, manipulate, and delete files. They also set and check file-access permissions.
File-handling routines work on a file designated by a path name or by a “file handle,” an integer assigned by the operating system that identifies an open file. These routines modify or give information about the designated file. Most of them are declared in the include file IO.H, with the exceptions being the _fstat and _stat functions (declared in SYS\STAT.H), the _fullpath routine (declared in DIRECT.H), and the remove and rename functions (also declared in STDIO.H).
| Routine | Use |
| _access | Checks file-permission setting |
| _chmod | Changes file-permission setting |
| _chsize | Changes file size |
| _filelength | Gets file length |
| _fstat | Gets file-status information on handle |
| _fullpath | Makes an absolute path name from a relative path name |
| _isatty | Checks for character device |
| _locking | Locks areas of file (available with DOS versions 3.0 and later) |
| _makepath | Merges path-name components into a single, full path name |
| _mktemp | Creates unique filename |
| remove | Deletes file |
| rename | Renames file |
| _setmode | Sets file-translation mode |
| _splitpath | Splits a path name into component pieces |
| _stat | Gets file-status information on named file |
| _umask | Sets default-permission mask |
| _unlink | Deletes file |
The _access, _chmod, _fullpath, _makepath, remove, rename, _splitpath, _stat, and _unlink routines operate on files specified by a path name or filename.
The _chsize, _filelength, _fstat, _isatty, _locking, and _setmode routines work with files designated by a file handle.
The _mktemp and _umask routines have functions that are slightly different from the other routines. The _mktemp routine creates a unique filename; you can use _mktemp to create unique filenames that do not conflict with the names of existing files. The _umask routine sets the default permission mask for any new files created in a program. The mask can override the permission setting given in the _open or _creat call for the new file.