- File Opening Flags
- File Properties
- In-File Position
- Use of a Codepage
- MessageBox
File Opening Flags
File opening flag values specify the file access mode. Flags are defined as follows:
Identifier |
Value |
Description |
|---|---|---|
FILE_READ |
1 |
File is opened for reading. Flag is used in FileOpen(). When opening a file specification of FILE_WRITE and/or FILE_READ is required. |
FILE_WRITE |
2 |
File is opened for writing. Flag is used in FileOpen(). When opening a file specification of FILE_WRITE and/or FILE_READ is required. |
FILE_BIN |
4 |
Binary read/write mode (without string to string conversion). Flag is used in FileOpen(). |
FILE_CSV |
8 |
CSV file (all its elements are converted to strings of the appropriate type, Unicode or ANSI, and separated by separator). Flag is used in FileOpen(). |
FILE_TXT |
16 |
Simple text file (the same as csv file, but without taking into account the separators). Flag is used in FileOpen(). |
FILE_ANSI |
32 |
Strings of ANSI type (one byte symbols). Flag is used in FileOpen(). |
FILE_UNICODE |
64 |
Strings of UNICODE type (two byte symbols). Flag is used in FileOpen(). |
FILE_SHARE_READ |
128 |
Shared access for reading from several programs. Flag is used in FileOpen(), but it does not replace the necessity to indicate FILE_WRITE and/or the FILE_READ flag when opening a file. |
FILE_SHARE_WRITE |
256 |
Shared access for writing from several programs. Flag is used in FileOpen(), but it does not replace the necessity to indicate FILE_WRITE and/or the FILE_READ flag when opening a file. |
FILE_REWRITE |
512 |
Possibility for the file rewrite using functions FileCopy() and FileMove(). The file should exist or should be opened for writing, otherwise the file will not be opened. |
FILE_COMMON |
4096 |
The file path in the common folder of all client terminals \Terminal\Common\Files. Flag is used in FileOpen(), FileCopy(), FileMove() and in FileIsExist() functions. |
One or several flags can be specified when opening a file. This is a combination of flags. The combination of flags is written using the sign of logical OR (|), which is positioned between enumerated flags. For example, to open a file in CSV format for reading and writing at the same time, specify the combination FILE_READ|FILE_WRITE|FILE_CSV.
Example:
int filehandle=FileOpen(filename,FILE_READ|FILE_WRITE|FILE_CSV); |
There are some specific features of work when you specify read and write flags:
- If FILE_READ is specified, an attempt is made to open an existing file. If a file does not exist, file opening fails, a new file is not created.
- FILE_READ|FILE_WRITE – a new file is created if the file with the specified name does not exist.
- FILE_WRITE – the file is created again with a zero size.
When opening a file, specification of FILE_WRITE and/or FILE_READ is required.
Flags that define the type of reading of an open file possess priority. The highest flag is FILE_CSV, then goes FILE_BIN, and FILE_TXT is of lowest priority. Thus, if several flags are specified at the same time, (FILE_TXT|FILE_CSV or FILE_TXT|FILE_BIN or FILE_BIN|FILE_CSV), the flag with the highest priority will be used.
Flags that define the type of encoding also have priority. FILE_UNICODE is of a higher priority than FILE_ANSI. So if you specify combination FILE_UNICODE|FILE_ANSI, flag FILE_UNICODE will be used.
If neither FILE_UNICODE nor FILE_ANSI is indicated, FILE_UNICODE is implied. If neither FILE_CSV, nor FILE_BIN, nor FILE_TXT is specified, FILE_CSV is implied.
If a file is opened for reading as a text file (FILE_TXT or FILE_CSV), and at the file beginning a special two-byte indication 0xff,0xfe is found, the encoding flag will be FILE_UNICODE, even if FILE_ANSI is specified.
See also