從指標到 EA

//+------------------------------------------------------------------+
//| Lesson 10 - First EA: new-bar gate, magic number, one entry      |
//| WARNING: sends real market orders. Use a DEMO account.           |
//+------------------------------------------------------------------+
#property copyright "Strategist Academy"
#property version   "1.00"
#property strict

#include <Trade/Trade.mqh>

input double Lots        = 0.10;
input int    StopPoints  = 200;
input ulong  MagicNumber = 10101010;

CTrade   trade;
datetime lastBarTime = 0;

int OnInit()
{
   trade.SetExpertMagicNumber(MagicNumber);
   trade.SetDeviationInPoints(10);
   trade.SetTypeFillingBySymbol(_Symbol);

   Print("Lesson 10 EA ready on ", _Symbol, " / ", EnumToString((ENUM_TIMEFRAMES)_Period));
   return(INIT_SUCCEEDED);
}

void OnTick()
{
   // 1) Only act on the first tick of a new bar.
   if(!IsNewBar())
      return;

   // 2) Never stack positions - check first.
   if(HasPosition(_Symbol, MagicNumber))
   {
      Print("Already in a position on ", _Symbol, " - standing down.");
      return;
   }

   // 3) Send the order and always log the retcode.
   double ask = SymbolInfoDouble(_Symbol, SYMBOL_ASK);
   double sl  = NormalizeDouble(ask - StopPoints * _Point, _Digits);

   bool ok = trade.Buy(Lots, _Symbol, 0.0, sl, 0.0, "lesson10");

   Print("Buy request ", ok ? "accepted" : "FAILED",
         "  retcode=", trade.ResultRetcode(),
         "  (", trade.ResultRetcodeDescription(), ")");

   if(ok)
      Print("Deal: ", trade.ResultDeal(), "  volume: ", trade.ResultVolume(),
            "  price: ", DoubleToString(trade.ResultPrice(), _Digits));
}

//+------------------------------------------------------------------+
//| Has the current bar's open time changed since we last looked?    |
//+------------------------------------------------------------------+
bool IsNewBar()
{
   datetime t = iTime(_Symbol, _Period, 0);
   if(t == lastBarTime)
      return false;
   lastBarTime = t;
   return true;
}

//+------------------------------------------------------------------+
//| Is there a position on this symbol carrying our magic number?    |
//+------------------------------------------------------------------+
bool HasPosition(const string sym, const ulong magic)
{
   if(!PositionSelect(sym))
      return false;
   return ((ulong)PositionGetInteger(POSITION_MAGIC) == magic);
}