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FileReadLong

The function reads an integer of long type (8 bytes) from the current position of the binary file.

long  FileReadLong(
   int  file_handle    // File handle
   );

Parameters

file_handle

[in]  File descriptor returned by FileOpen().

Return Value

The value of long type.

Example (the file obtained during the execution of an example for FileWriteLong function is used here)

//+------------------------------------------------------------------+
//|                                            Demo_FileReadLong.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"
#property indicator_buffers 1
#property indicator_plots   1
//---- plot Label1
#property indicator_label1  "Volume"
#property indicator_type1   DRAW_LINE
#property indicator_color1  clrYellow
#property indicator_style1  STYLE_SOLID
#property indicator_width1  2
#property indicator_separate_window
//--- parameters for data reading
input string InpFileName="Volume.bin"// file name
input string InpDirectoryName="Data";  // directory name
//--- global variables
int      ind=0;
int      size=0;
long     volume_buff[];
datetime time_buff[];
//--- indicator buffers
double   buff[];
//+------------------------------------------------------------------+
//| Custom indicator initialization function                         |
//+------------------------------------------------------------------+
int OnInit()
  {
//--- open the file
   ResetLastError();
   int file_handle=FileOpen(InpDirectoryName+"//"+InpFileName,FILE_READ|FILE_BIN);
   if(file_handle!=INVALID_HANDLE)
     {
      PrintFormat("%s file is open for writing",InpFileName);
      PrintFormat("File path: %s\\Files\\",TerminalInfoString(TERMINAL_DATA_PATH));
      //--- first, read the amount of data in the file
      size=(int)FileReadLong(file_handle);
      //--- allocate memory for the arrays
      ArrayResize(volume_buff,size);
      ArrayResize(time_buff,size);
      //--- read data from the file
      for(int i=0;i<size;i++)
        {
         time_buff[i]=(datetime)FileReadLong(file_handle);
         volume_buff[i]=FileReadLong(file_handle);
        }
      //--- close the file
      FileClose(file_handle);
      PrintFormat("Data is read, %s file is closed",InpFileName);
     }
   else
     {
      PrintFormat("Failed to open %s file, Error code = %d",InpFileName,GetLastError());
      return(INIT_FAILED);
     }
//--- bind the array to the indicator buffer with 0 index
   SetIndexBuffer(0,buff,INDICATOR_DATA);
//---- set the indicator values that will be visible on the chart
   PlotIndexSetDouble(0,PLOT_EMPTY_VALUE,0);
//---
   return(INIT_SUCCEEDED);
  }
//+------------------------------------------------------------------+
//| Custom indicator iteration function                              |
//+------------------------------------------------------------------+
int OnCalculate(const int rates_total,
                const int prev_calculated,
                const datetime &time[],
                const double &open[],
                const double &high[],
                const double &low[],
                const double &close[],
                const long &tick_volume[],
                const long &volume[],
                const int &spread[])
  {
   ArraySetAsSeries(time,false);
//--- the loop for the bars that have not been handled yet
   for(int i=prev_calculated;i<rates_total;i++)
     {
      //--- 0 by default
      buff[i]=0;
      //--- check if any data is still present
      if(ind<size)
        {
         for(int j=ind;j<size;j++)
           {
            //--- if dates coincide, the value from the file is used
            if(time[i]==time_buff[j])
              {
               buff[i]=(double)volume_buff[j];
               ind=j+1;
               break;
              }
           }
        }
     }
//--- return value of prev_calculated for next call
   return(rates_total);
  }

See also

Integer types, FileReadInteger, FileWriteLong


Updated: 2015.12.03