//+------------------------------------------------------------------+
//|                                                          SMA.mq4 |
//|                                                                  |
//|                                                                  |
//+------------------------------------------------------------------+

#property indicator_chart_window
#property indicator_buffers 1
#property indicator_color1 DodgerBlue
//---- input parameters
 extern int period = 14;
//---- buffer
 double Buffer[]; 
//+------------------------------------------------------------------+
//| Custom indicator initialization function                         |
//+------------------------------------------------------------------+
int init()
  {
//---- 1 additional buffer used for counting.
   IndicatorBuffers( 1 );
   IndicatorDigits( Digits );
//---- indicator line
   SetIndexStyle( 0, DRAW_LINE );
   SetIndexBuffer( 0, Buffer );
//---- name for DataWindow and indicator subwindow label
   string short_name = "SMA("+period+")";
   IndicatorShortName( short_name );
   SetIndexLabel( 0, short_name );
//----
   return(0);
  }
//+------------------------------------------------------------------+
//| Custom indicator deinitialization function                       |
//+------------------------------------------------------------------+
int deinit()
  {
//----
   
//----
   return(0);
  }
//+------------------------------------------------------------------+
//| Custom indicator iteration function                              |
//+------------------------------------------------------------------+
int start()
  {
//----
     double sum;
     int counted_bars = IndicatorCounted( );   
     //---- последний посчитанный бар будет пересчитан
     if ( counted_bars > 0 ) counted_bars--;
     int limit = Bars-counted_bars-1;
     //---- основной цикл 
      
       for ( int i = 0; i <= limit; i++ ) 
       { 
           if ( i >= period )
           { 
            Buffer[i - period] = sum / period;
            sum = sum + Close[i] - Close[i - period];            
           }
           else
           {
           if ( i < period )
           {
            sum = sum + Close[i];
           }
           }        
       }

   
//----
   return(0);
  }
//+------------------------------------------------------------------+