迴圈：有效率地掃描 K 線

//+------------------------------------------------------------------+
//| Lesson 7 - Loops: range scan and streak count                    |
//+------------------------------------------------------------------+
#property copyright "Strategist Academy"
#property version   "1.00"

void OnStart()
{
   int lookback = 20;

   MqlRates rates[];
   ArraySetAsSeries(rates, true);          // index 0 = newest bar

   int copied = CopyRates(_Symbol, _Period, 0, lookback + 1, rates);
   if(copied < lookback + 1)
   {
      Print("CopyRates returned ", copied, " bars - expected ", lookback + 1,
            ". Error: ", GetLastError());
      return;
   }

   // Start at 1: bar 0 is still forming, so it is not a completed range.
   double highest = rates[1].high;
   double lowest  = rates[1].low;
   int    highBar = 1;
   int    lowBar  = 1;

   for(int i = 2; i <= lookback && !IsStopped(); i++)
   {
      if(rates[i].high > highest) { highest = rates[i].high; highBar = i; }
      if(rates[i].low  < lowest)  { lowest  = rates[i].low;  lowBar  = i; }
   }

   Print("Range over last ", lookback, " completed bars on ", _Symbol);
   Print("Highest high: ", DoubleToString(highest, _Digits), "  (", highBar, " bars ago)");
   Print("Lowest low:   ", DoubleToString(lowest, _Digits), "  (", lowBar, " bars ago)");
   Print("Range size:   ", DoubleToString((highest - lowest) / _Point, 1), " points");

   // while loop: how many consecutive completed closes sit above the midpoint?
   double mid    = (highest + lowest) / 2.0;
   int    streak = 0;
   int    i      = 1;

   while(i <= lookback && rates[i].close > mid)
   {
      streak++;
      i++;
   }

   Print("Consecutive closes above midpoint: ", streak, " of ", lookback);
}