FileWriteArray
FileWriteArray
The function writes arrays of any type except for string to a BIN file (can be an array of structures not containing strings or dynamic arrays).
uint FileWriteArray(
int file_handle, // File handle
const void& array[], // Array
int start=0, // Start index in the array
int count=WHOLE_ARRAY // Number of elements
);Parameters
- file_handle
[in] File descriptor returned by FileOpen().
- array[]
[out] Array for recording.
- start=0
[in] Initial index in the array (number of the first recorded element).
- count=WHOLE_ARRAY
[in] Number of items to write (WHOLE_ARRAY means that all items starting with the number start until the end of the array will be written).
Return Value
Number of recorded items.
Note
String array can be recorded in a TXT file. In this case, strings are automatically ended by the line end characters “\r\n”. Depending on the file type ANSI or UNICODE, strings are either converted to ansi-encoding or not.
Example:
//+------------------------------------------------------------------+
//| Demo_FileWriteArray.mq5 |
//| Copyright 2013, MetaQuotes Software Corp. |
//| https://www.mql5.com |
//+------------------------------------------------------------------+
#property copyright "Copyright 2013, MetaQuotes Software Corp."
#property link "https://www.mql5.com"
#property version "1.00"
//--- input parameters
input string InpFileName="data.bin";
input string InpDirectoryName="SomeFolder";
//+------------------------------------------------------------------+
//| Structure for storing price data |
//+------------------------------------------------------------------+
struct prices
{
datetime date; // date
double bid; // bid price
double ask; // ask price
};
//--- global variables
int count=0;
int size=20;
string path=InpDirectoryName+"//"+InpFileName;
prices arr[];
//+------------------------------------------------------------------+
//| Expert initialization function |
//+------------------------------------------------------------------+
int OnInit()
{
//--- allocate memory for the array
ArrayResize(arr,size);
//---
return(INIT_SUCCEEDED);
}
//+------------------------------------------------------------------+
//| Expert deinitialization function |
//+------------------------------------------------------------------+
void OnDeinit(const int reason)
{
//--- write the remaining count strings if count<n
WriteData(count);
}
//+------------------------------------------------------------------+
//| Expert tick function |
//+------------------------------------------------------------------+
void OnTick()
{
//--- save data to array
arr[count].date=TimeCurrent();
arr[count].bid=SymbolInfoDouble(Symbol(),SYMBOL_BID);
arr[count].ask=SymbolInfoDouble(Symbol(),SYMBOL_ASK);
//--- show current data
Print("Date = ",arr[count].date," Bid = ",arr[count].bid," Ask = ",arr[count].ask);
//--- increase the counter
count++;
//--- if the array is filled, write data to the file and zero it out
if(count==size)
{
WriteData(size);
count=0;
}
}
//+------------------------------------------------------------------+
//| Write n elements of the array to file |
//+------------------------------------------------------------------+
void WriteData(const int n)
{
//--- open the file
ResetLastError();
int handle=FileOpen(path,FILE_READ|FILE_WRITE|FILE_BIN);
if(handle!=INVALID_HANDLE)
{
//--- write array data to the end of the file
FileSeek(handle,0,SEEK_END);
FileWriteArray(handle,arr,0,n);
//--- close the file
FileClose(handle);
}
else
Print("Failed to open the file, error ",GetLastError());
}See also
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