What's the use of the 1st assignment?

[Weixing Meng]

Thanks a lot for help

input double Lots           =0.1;   //at the ea start, enter the parameter 0.1 here

//and then there is a "lot" in the block following, there are two assignments for"lot", then what's the 1st assignment for?
double LotsOptimized()
  {
   double lot=Lots;   // the 1st
   int    orders=OrdersHistoryTotal();     // history orders total
   int    losses=0;                  // number of losses orders without a break
//--- select lot size
   lot=NormalizeDouble(AccountFreeMargin()*MaximumRisk/1000.0,1);  // the 2nd
//--- calcuulate number of losses orders without a break
   if(DecreaseFactor>0)
     {
      for(int i=orders-1;i>=0;i--)
        {
         if(OrderSelect(i,SELECT_BY_POS,MODE_HISTORY)==false)
           {
            Print("Error in history!");
            break;
           }
         if(OrderSymbol()!=Symbol() || OrderType()>OP_SELL)
            continue;
         //---
         if(OrderProfit()>0) break;
         if(OrderProfit()<0) losses++;
        }
      if(losses>1)
         lot=NormalizeDouble(lot-lot*losses/DecreaseFactor,1);
     }
//--- return lot size
   if(lot<0.1) lot=0.1;
   return(lot);
  }

[Weixing Meng]

It give the "Lots" we entered to lot first, and then give a value to lot again according to account free margin, the previous value is covered by it right? so is that necessary to enter a Lots at the EA start ?

It's from the sample Moving Average EA in MT4 program.

I took course of C programming...and back here again lol.. 

[William Roeder]

1. lot is not used between the 1st and 2nd.	double lot=Lots;   // the 1st    int    orders=OrdersHistoryTotal();     // history orders total    int    losses=0;                  // number of losses orders without a break //--- select lot size    lot=NormalizeDouble(AccountFreeMargin()*MaximumRisk/1000.0,1);  // the 2nd
   So remove it. And then check if Lots is used anywhere.	int    orders=OrdersHistoryTotal();     // history orders total    int    losses=0;                  // number of losses orders without a break //--- select lot size    double lot=NormalizeDouble(AccountFreeMargin()*MaximumRisk/1000.0,1);  // once

   ---

2. Calculate your risk properly.
   • You place the stop where it needs to be - where the reason for the trade is no longer valid. E.g. trading a support bounce the stop goes below the support.
   • Account Balance * percent/100 = RISK = OrderLots * (|OrderOpenPrice - OrderStopLoss| * DeltaPerLot + CommissionPerLot) (Note OOP-OSL includes the SPREAD, and DeltaPerLot is usually around $10/pip)
   • Do NOT use TickValue by itself - DeltaPerLot
   • You must normalize lots properly and check against min and max.
     
   • You must also check FreeMargin to avoid stop out