OnCalculate function not found in custom indicator?

[joshatt]

There's a given Moving Average indicator, it works in MT5. Now I'm trying to add a text object tagging the MA value of last bar.

#property indicator_chart_window
#property indicator_buffers 1
#property indicator_plots   1
#property indicator_type1   DRAW_LINE
#property indicator_color1  clrWhite

input int            InpMAPeriod=144;         // Period
input ENUM_MA_METHOD InpMAMethod=MODE_EMA;  // Method

double ExtLineBuffer[];
//+------------------------------------------------------------------+
//| Custom indicator initialization function                         |
//+------------------------------------------------------------------+
void OnInit()
  {
//--- indicator buffers mapping
   SetIndexBuffer(0,ExtLineBuffer,INDICATOR_DATA);
//--- set accuracy
   IndicatorSetInteger(INDICATOR_DIGITS,_Digits+1);
//--- name for DataWindow
   string short_name;
   switch(InpMAMethod)
     {
      case MODE_EMA :
         short_name="EMA";
      default :
         short_name="ma";
     }
   IndicatorSetString(INDICATOR_SHORTNAME,short_name+"("+string(InpMAPeriod)+")");
//--- set drawing line empty value
   PlotIndexSetDouble(0,PLOT_EMPTY_VALUE,0.0);
  }



//+------------------------------------------------------------------+
//|                                                                  |
//+------------------------------------------------------------------+

void OnDeinit(const int reason)
  {
   if(ObjectFind(0,"lastmapricetag")>=0)
     {
      ObjectDelete(0,"lastmapricetag");
     }
  }
  
//+------------------------------------------------------------------+
//|  Moving Average                                                  |
//+------------------------------------------------------------------+
int OnCalculate(const int rates_total,
                const int prev_calculated,
                const int begin,
                const datetime &time[],
                const double &price[])
  {
   if(rates_total<InpMAPeriod-1+begin)
      return(0);
//--- first calculation or number of bars was changed
   if(prev_calculated==0)
     {
      ArrayInitialize(ExtLineBuffer,0);
      PlotIndexSetInteger(0,PLOT_DRAW_BEGIN,InpMAPeriod-1+begin);
     }
//--- calculation
   switch(InpMAMethod)
     {
      case MODE_EMA:
         CalculateEMA(rates_total,prev_calculated,begin,price);
         break;
     }





   ObjectCreate(0,"lastmapricetag",OBJ_TEXT,0,time[rates_total-1],ExtLineBuffer[rates_total-1]);



//--- return value of prev_calculated for next call
   return(rates_total);
  }
//+------------------------------------------------------------------+
//|  exponential moving average                                      |
//+------------------------------------------------------------------+
void CalculateEMA(int rates_total,int prev_calculated,int begin,const double &price[])
  {
   int    i,start;
   double SmoothFactor=2.0/(1.0+InpMAPeriod);
//--- first calculation or number of bars was changed
   if(prev_calculated==0)
     {
      start=InpMAPeriod+begin;
      ExtLineBuffer[begin]=price[begin];
      for(i=begin+1; i<start; i++)
         ExtLineBuffer[i]=price[i]*SmoothFactor+ExtLineBuffer[i-1]*(1.0-SmoothFactor);
     }
   else
      start=prev_calculated-1;
//--- main loop
   for(i=start; i<rates_total && !IsStopped(); i++)
      ExtLineBuffer[i]=price[i]*SmoothFactor+ExtLineBuffer[i-1]*(1.0-SmoothFactor);
  }
//+------------------------------------------------------------------+

As shown in the code, I only added 3 things:

const datetime &time[],   (in OnCalculate defination)

void OnDeinit(...)....

ObjectCreate(....)

I don't know, it must have been " const datetime &time[],  " that caused the error?

BTW, I do not understand the original source code - what does "price[]" mean? where does it come from?