Keltner Channels_v3

//+------------------------------------------------------------------+
//|                                             Keltner Channels.mq4 |
//|                                                  Coded by Gilani |
//|                      Copyright © 2005, MetaQuotes Software Corp. |
//|                                        http://www.metaquotes.net |
//+------------------------------------------------------------------+
#property copyright "Copyright © 2005, MetaQuotes Software Corp."
#property link      "http://www.metaquotes.net"
//+------------------------------------------------------------------+
//| Custom indicator initialization function                         |
//+------------------------------------------------------------------+
#property indicator_chart_window
#property indicator_buffers 3
#property indicator_color1 Red
#property indicator_color2 Green
#property indicator_color3 Black
//----
double upper[], middle[], lower[];
extern int period=10;
//----
//+------------------------------------------------------------------+
//|                                                                  |
//+------------------------------------------------------------------+
int init()
  {
   SetIndexStyle(0,DRAW_LINE);
   SetIndexShift(0,0);
   SetIndexDrawBegin(0,0);
   SetIndexBuffer(0,upper);
   SetIndexStyle(1,DRAW_LINE);
   SetIndexShift(1,0);
   SetIndexDrawBegin(1,0);
   SetIndexBuffer(1,middle);
   SetIndexStyle(2,DRAW_LINE);
   SetIndexShift(2,0);
   SetIndexDrawBegin(2,0);
   SetIndexBuffer(2,lower);
//---- indicators
//----
   return(0);
  }
//+------------------------------------------------------------------+
//| Custor indicator deinitialization function                       |
//+------------------------------------------------------------------+
int deinit()
  {
//---- TODO: add your code here
//----
   return(0);
  }
//+------------------------------------------------------------------+
//| Custom indicator iteration function                              |
//+------------------------------------------------------------------+
  int start() 
  {
   int limit;
   int counted_bars=IndicatorCounted();
   if(counted_bars<0) return(-1);
   if(counted_bars>0) counted_bars--;
   limit=Bars-counted_bars;
//----
   double avg;
     for(int x=0; x<limit; x++) 
     {
      middle[x]=iMA(NULL, 0, period, 0, MODE_SMA, PRICE_TYPICAL, x);
      avg =findAvg(period, x);
      upper[x]=middle[x] + avg;
      lower[x]=middle[x] - avg;
     }
   return(0);
  }
//+------------------------------------------------------------------+
  double findAvg(int period, int shift) 
  {
   double sum=0;
     for(int x=shift;x<(shift+period);x++) 
     {
      sum+=High[x]-Low[x];
     }
   sum=sum/period;
   return(sum);
  }
//+------------------------------------------------------------------+