WPR_v2

//+------------------------------------------------------------------+
//|                                      Williams’ Percent Range.mq4 |
//|                      Copyright © 2005, MetaQuotes Software Corp. |
//|                                       http://www.metaquotes.net/ |
//+------------------------------------------------------------------+
#property copyright "Copyright © 2005, MetaQuotes Software Corp."
#property link      "http://www.metaquotes.net/"

#property indicator_separate_window
#property indicator_minimum -100
#property indicator_maximum 0
#property indicator_buffers 1
#property indicator_color1 DodgerBlue
#property indicator_level1 -20
#property indicator_level2 -80
//---- input parameters
extern int ExtWPRPeriod=14;
//---- buffers
double ExtWPRBuffer[];
//+------------------------------------------------------------------+
//| Custom indicator initialization function                         |
//+------------------------------------------------------------------+
int init()
  {
   string sShortName;
//---- indicator buffer mapping
   SetIndexBuffer(0,ExtWPRBuffer);
//---- indicator line
   SetIndexStyle(0,DRAW_LINE);
//---- name for DataWindow and indicator subwindow label
   sShortName="%R("+ExtWPRPeriod+")";
   IndicatorShortName(sShortName);
   SetIndexLabel(0,sShortName);
//---- first values aren't drawn
   SetIndexDrawBegin(0,ExtWPRPeriod);
//----
   return(0);
  }
//+------------------------------------------------------------------+
//| Williams’ Percent Range                                          |
//+------------------------------------------------------------------+
int start()
  {
   int i,nLimit,nCountedBars;  
//---- insufficient data
   if(Bars<=ExtWPRPeriod) return(0);
//---- bars count that does not changed after last indicator launch.
   nCountedBars=IndicatorCounted();
//----Williams’ Percent Range calculation
   i=Bars-ExtWPRPeriod-1;
   if(nCountedBars>ExtWPRPeriod) 
      i=Bars-nCountedBars-1;  
   while(i>=0)
     {
      double dMaxHigh=High[Highest(NULL,0,MODE_HIGH,ExtWPRPeriod,i)];
      double dMinLow=Low[Lowest(NULL,0,MODE_LOW,ExtWPRPeriod,i)];      
      ExtWPRBuffer[i]=-100*(dMaxHigh-Close[i])/(dMaxHigh-dMinLow);
      i--;
     }
//----
   return(0);
  }
//+------------------------------------------------------------------+