MQL5 - Language of trade strategies built-in the MetaTrader 5 client terminal

Automated Trading Language Documentation

Buy Expert Advisors in MetaTrader Market and Let Them Trade For You

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

File Functions


Updated: 2014.07.29