Article-16308-MQL5-Moving-Average-From-Scratch/SMA/SMAonPriceClose.mq5

<EFBFBD><EFBFBD>//+------------------------------------------------------------------+
//|                                              SMAonPriceClose.mq5 |
//|                                  Copyright 2024, MetaQuotes Ltd. |
//|                                             https://www.mql5.com |
//+------------------------------------------------------------------+
#property copyright "Copyright 2024, MetaQuotes Ltd."
#property link      "https://www.mql5.com"
#property version   "1.00"
#property indicator_chart_window
#property indicator_buffers 1
#property indicator_plots   1

//--- plot MA
#property indicator_label1  "SMA"
#property indicator_type1   DRAW_LINE
#property indicator_color1  clrRed
#property indicator_style1  STYLE_SOLID
#property indicator_width1  1

//--- input parameters
input int      InpPeriod   =  10;   // SMA Period

//--- indicator buffers
double         MABuffer[];

//--- global variables
int   ExtPeriod;  // ?5@8>4 @0AGQB0 SMA
//+------------------------------------------------------------------+
//| Custom indicator initialization function                         |
//+------------------------------------------------------------------+
int OnInit()
  {
//--- indicator buffers mapping
   SetIndexBuffer(0,MABuffer,INDICATOR_DATA);
   
//--- CA?5H=0O 8=8F80;870F8O
   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[])
  {
//--- >@@5:B8@C5< 2254Q==>5 7=0G5=85 ?5@8>40 @0AGQB0 SMA
   ExtPeriod=(InpPeriod<1 ? 10 : InpPeriod);
   
//--- A;8 =5 E20B05B 8AB>@8G5A:8E 40==KE 4;O @0AGQB0 - 2>72@0I05< 0
   if(rates_total<ExtPeriod)
      return 0;
      
   int start=0;   // 10@ =0G0;0 @0AGQB0
   
//--- A;8 MB> ?5@2K9 70?CA: 8;8 87<5=5=85 2 8AB>@8G5A:8E 40==KE
   if(prev_calculated==0)
     {
      //--- 8=8F80;878@C5< 1CD5@ 8=48:0B>@0 ?CABK< 7=0G5=85<,
      //--- CAB0=02;8205< =0G0;> @0AGQB0 =0 7=0G5=85 ExtPeriod 8
      //--- @0AAG8BK205< A@54=55 F5= close 70 ExtPeriod 10@>2 4;O ?5@2>3> 7=0G5=8O SMA =0 10@5 start-1
      ArrayInitialize(MABuffer,EMPTY_VALUE);
      start=ExtPeriod;
      double value=0;
      for(int i=0; i<start; i++)
         value+=close[i];
      MABuffer[start-1]=value/ExtPeriod;
     }
//--- A;8 MB> =5 ?5@2K9 70?CA: - =0G0;>< @0AGQB0 1C45B B5:CI89 10@
   else
      start=prev_calculated-1;
      
//--- 2 F8:;5 >B 7=0G5=8O start 4> B5:CI53> 10@0 8AB>@88
   for(int i=start; i<rates_total; i++)
     {
      //--- >?@545;O5< F5=K 4;O @0AGQB0 SMA
      double ma_prev=MABuffer[i-1];             // @54K4CI55 @0AAG8B0==>5 7=0G5=85 SMA
      double price_first=close[i-ExtPeriod];    // &5=0 close ExtPeriod 10@>2 =0704
      //--- 0?8AK205< 2 1CD5@ B5:CI55 7=0G5=85 SMA, @0AAG8B0==>5 :0: 
      //--- (?@>H;>5 7=0G5=85 SMA + (B5:CI0O F5=0 close - F5=0 close ExtPeriod 10@>2 =0704) / ?5@8>4 @0AGQB0 SMA ExtPeriod)
      MABuffer[i]=ma_prev+(close[i]-price_first)/ExtPeriod;
     }
     
//--- 2>72@0I05< :>;8G5AB2> ?>AG8B0==KE 10@>2 4;O A;54CNI53> 2K7>20 OnCalculate
   return(rates_total);
  }
//+------------------------------------------------------------------+