File Functions

This is a group of functions for working with files.

For security reasons, work with files is strictly controlled in the MQL4 language. Files with which file operations are conducted using MQL4 means cannot be outside the file sandbox.

There are two directories (with subdirectories) in which working files can be located:

terminal_data_folder\MQL4\Files\ (in the terminal menu select to view “File” - “Open the data directory”);
the common folder for all the terminals installed on a computer - usually located in the directory C:\Documents and Settings\All Users\Application Data\MetaQuotes\Terminal\Common\Files.

There is a program method to obtain names of these catalogs using the TerminalInfoString() function, using the ENUM_TERMINAL_INFO_STRING enumeration:

//--- Folder that stores the terminal data
   string terminal_data_path=TerminalInfoString(TERMINAL_DATA_PATH);
//--- Common folder for all client terminals
   string common_data_path=TerminalInfoString(TERMINAL_COMMONDATA_PATH);

Work with files from other directories is prohibited.

File functions allow working with so-called “named pipes”. To do this, simply call FileOpen() function with appropriate parameters.

Function	Action
FileFindFirst	Starts the search of files in a directory in accordance with the specified filter
FileFindNext	Continues the search started by the FileFindFirst() function
FileFindClose	Closes search handle
FileOpen	Opens a file with a specified name and flag
FileDelete	Deletes a specified file
FileFlush	Writes to a disk all data remaining in the input/output file buffer
FileGetInteger	Gets an integer property of a file
FileIsEnding	Defines the end of a file in the process of reading
FileIsLineEnding	Defines the end of a line in a text file in the process of reading
FileClose	Closes a previously opened file
FileIsExist	Checks the existence of a file
FileCopy	Copies the original file from a local or shared folder to another file
FileMove	Moves or renames a file
FileReadArray	Reads arrays of any type except for string from the file of the BIN type
FileReadBool	Reads from the file of the CSV type a string from the current position till a delimiter (or till the end of a text line) and converts the read string to a value of bool type
FileReadDatetime	Reads from the file of the CSV type a string of one of the formats: “YYYY.MM.DD HH:MM:SS”, “YYYY.MM.DD” or “HH:MM:SS” - and converts it into a datetime value
FileReadDouble	Reads a double value from the current position of the file pointer
FileReadFloat	Reads a float value from the current position of the file pointer
FileReadInteger	Reads int, short or char value from the current position of the file pointer
FileReadLong	Reads a long type value from the current position of the file pointer
FileReadNumber	Reads from the file of the CSV type a string from the current position till a delimiter (or til the end of a text line) and converts the read string into double value
FileReadString	Reads a string from the current position of a file pointer from a file
FileReadStruct	Reads the contents from a binary file into a structure passed as a parameter, from the current position of the file pointer
FileSeek	Moves the position of the file pointer by a specified number of bytes relative to the specified position
FileSize	Returns the size of a corresponding open file
FileTell	Returns the current position of the file pointer of a corresponding open file
FileWrite	Writes data to a file of CSV or TXT type
FileWriteArray	Writes arrays of any type except for string into a file of BIN type
FileWriteDouble	Writes value of the double type from the current position of a file pointer into a binary file
FileWriteFloat	Writes value of the float type from the current position of a file pointer into a binary file
FileWriteInteger	Writes value of the int type from the current position of a file pointer into a binary file
FileWriteLong	Writes value of the long type from the current position of a file pointer into a binary file
FileWriteString	Writes the value of a string parameter into a BIN or TXT file starting from the current position of the file pointer
FileWriteStruct	Writes the contents of a structure passed as a parameter into a binary file, starting from the current position of the file pointer
FolderCreate	Creates a folder in the Files directory
FolderDelete	Removes a selected directory. If the folder is not empty, then it can’t be removed
FolderClean	Deletes all files in the specified folder
FileOpenHistory	Opens file in the current history directory or in its subfolders

If the file is opened for writing using FileOpen(), all subfolders specified in the path will be created if there are no such ones.

Last updated on 2026-06-26