MQL4参考文件函数 FileReadArray

FileReadArray

Reads from a file of BIN type arrays of any type except string (may be an array of structures, not containing strings, and dynamic arrays).

uint  FileReadArray(
   int    file_handle,               // File handle
   void&  array[],                   // Array to record
   int    start=0,                   // start array position to write
   int    count=WHOLE_ARRAY          // count to read
   );

Parameters

file_handle

[in] File descriptor returned by FileOpen().

array[]

[out] An array where the data will be loaded.

start=0

[in] Start position to read from the array.

count=WHOLE_ARRAY

[in] Number of elements to read. By default, reads the entire array (count=WHOLE_ARRAY).

Return Value

Number of elements read or 0 in case of error. To obtain information about the error, call the GetLastError() function. By default the count=WHOLE_ARRAY elements will be read.

Note

String array can be read only from the file of TXT type. If necessary, the function tries to increase the size of the array.

Example (the file obtained after execution of the example for FileWriteArray() function is used here)

//--- display the window of input parameters when launching the script
#property script_show_inputs
//--- 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
  };
//+------------------------------------------------------------------+
//| Script program start function                                    |
//+------------------------------------------------------------------+
void OnStart()
  {
//--- structure array
   prices arr[];
//--- file path
   string path=InpDirectoryName+"//"+InpFileName;
//--- open the file
   ResetLastError();
   int file_handle=FileOpen(path,FILE_READ|FILE_BIN);
   if(file_handle!=INVALID_HANDLE)
     {
      //--- read all data from the file to the array
      FileReadArray(file_handle,arr);
      //--- receive the array size
      int size=ArraySize(arr);
      //--- print data from the array
      for(int i=0;i<size;i++)
         Print("Date = ",arr[i].date," Bid = ",arr[i].bid," Ask = ",arr[i].ask);
      Print("Total data = ",size);
      //--- close the file
      FileClose(file_handle);
     }
   else
      Print("File open failed, error ",GetLastError());
  }