How to Code a Stochastic Crossover Strategy in an Mql4 EA

Here is a complete, fully functional Expert Advisor (EA) for MetaTrader 4 written in MQL4.

This EA implements a Stochastic Crossover Strategy. It enters a Buy trade when the Main line crosses above the Signal line, and a Sell trade when the Main line crosses below the Signal line.

Strategy Logic

1. Buy Signal: The Main Stochastic line was below the Signal line on the previous candle, but is above it on the current closed candle.
2. Sell Signal: The Main Stochastic line was above the Signal line on the previous candle, but is below it on the current closed candle.
3. Execution: The EA checks signals on closed bars (Shift 1 and Shift 2) to prevent "repainting" (where a signal appears and disappears while the current candle is still forming).

MQL4 Code

//+------------------------------------------------------------------+
//|                                          Stochastic_Crossover_EA.mq4 |
//|                        Copyright 2023, Quantitative Trading Assistant |
//|                                             https://www.mql5.com |
//+------------------------------------------------------------------+
#property copyright "Copyright 2023, Quantitative Trading Assistant"
#property link      "https://www.mql5.com"
#property version   "1.00"
#property strict

//--- Input Parameters
input double Lots          = 0.1;      // Fixed Lot Size
input int    StopLoss      = 50;       // Stop Loss in pips (0 = no SL)
input int    TakeProfit    = 100;      // Take Profit in pips (0 = no TP)
input int    MagicNumber   = 12345;    // Unique Identifier for this EA
input int    Slippage      = 3;        // Max slippage in pips

//--- Stochastic Settings
input int    K_Period      = 5;        // %K Period
input int    D_Period      = 3;        // %D Period
input int    Slowing       = 3;        // Slowing
input ENUM_MA_METHOD MA_Method = MODE_SMA; // MA Method
input ENUM_STO_PRICE Price_Field = 0;      // Price Field (0=Low/High, 1=Close/Close)

//--- Global Variables
double pips;

//+------------------------------------------------------------------+
//| Expert initialization function                                   |
//+------------------------------------------------------------------+
int OnInit()
{
   // Adjust pips for 4 or 5 digit brokers
   if(Digits == 3 || Digits == 5) pips = Point * 10;
   else pips = Point;
   
   return(INIT_SUCCEEDED);
}

//+------------------------------------------------------------------+
//| Expert tick function                                             |
//+------------------------------------------------------------------+
void OnTick()
{
   // Check if we have enough bars to calculate
   if(Bars < 100) return;

   // 1. Get Stochastic Values for the last closed bar (Shift 1) and the one before (Shift 2)
   // We use closed bars to ensure the crossover is confirmed and won't repaint.
   
   // Main Line
   double main_1 = iStochastic(NULL, 0, K_Period, D_Period, Slowing, MA_Method, Price_Field, MODE_MAIN, 1);
   double main_2 = iStochastic(NULL, 0, K_Period, D_Period, Slowing, MA_Method, Price_Field, MODE_MAIN, 2);
   
   // Signal Line
   double sig_1  = iStochastic(NULL, 0, K_Period, D_Period, Slowing, MA_Method, Price_Field, MODE_SIGNAL, 1);
   double sig_2  = iStochastic(NULL, 0, K_Period, D_Period, Slowing, MA_Method, Price_Field, MODE_SIGNAL, 2);

   // 2. Check for Crossover Signals
   bool buySignal  = (main_2 < sig_2) && (main_1 > sig_1); // Crossed Up
   bool sellSignal = (main_2 > sig_2) && (main_1 < sig_1); // Crossed Down

   // 3. Manage Trades
   // Check if we already have an open position for this symbol and magic number
   if(CountOpenTrades() == 0)
   {
      if(buySignal)
      {
         OpenBuy();
      }
      else if(sellSignal)
      {
         OpenSell();
      }
   }
}

//+------------------------------------------------------------------+
//| Helper: Count Open Trades for this EA                            |
//+------------------------------------------------------------------+
int CountOpenTrades()
{
   int count = 0;
   for(int i = OrdersTotal() - 1; i >= 0; i--)
   {
      if(OrderSelect(i, SELECT_BY_POS, MODE_TRADES))
      {
         if(OrderSymbol() == Symbol() && OrderMagicNumber() == MagicNumber)
         {
            count++;
         }
      }
   }
   return count;
}

//+------------------------------------------------------------------+
//| Helper: Open Buy Order                                           |
//+------------------------------------------------------------------+
void OpenBuy()
{
   double sl = (StopLoss > 0) ? Ask - StopLoss * pips : 0;
   double tp = (TakeProfit > 0) ? Ask + TakeProfit * pips : 0;
   
   // Normalize prices to prevent errors
   sl = NormalizeDouble(sl, Digits);
   tp = NormalizeDouble(tp, Digits);

   int ticket = OrderSend(Symbol(), OP_BUY, Lots, Ask, Slippage, sl, tp, "Stoch Buy", MagicNumber, 0, clrBlue);
   
   if(ticket < 0)
   {
      Print("OrderSend failed with error #", GetLastError());
   }
}

//+------------------------------------------------------------------+
//| Helper: Open Sell Order                                          |
//+------------------------------------------------------------------+
void OpenSell()
{
   double sl = (StopLoss > 0) ? Bid + StopLoss * pips : 0;
   double tp = (TakeProfit > 0) ? Bid - TakeProfit * pips : 0;
   
   // Normalize prices to prevent errors
   sl = NormalizeDouble(sl, Digits);
   tp = NormalizeDouble(tp, Digits);

   int ticket = OrderSend(Symbol(), OP_SELL, Lots, Bid, Slippage, sl, tp, "Stoch Sell", MagicNumber, 0, clrRed);
   
   if(ticket < 0)
   {
      Print("OrderSend failed with error #", GetLastError());
   }
}
//+------------------------------------------------------------------+

How to Install and Use

1. Open MetaTrader 4.
2. Press F4 to open the MetaEditor.
3. Click New -> Expert Advisor (template) -> Name it "Stochastic_Crossover".
4. Delete everything in the new file and paste the code above.
5. Press F7 or click Compile. Ensure there are no errors.
6. Go back to the MT4 terminal. The EA will appear in the Navigator window under Expert Advisors.
7. Drag the EA onto a chart.
8. Ensure the "Allow live trading" box is checked in the Common tab.

Key Features of This Code

• No Repainting: It uses Shift 1 (the last closed candle) and Shift 2 (the candle before that) to detect the crossover. This ensures the signal is permanent and won't vanish if the price moves before the current candle closes.
• Broker Compatibility: It automatically detects if your broker uses 4-digit or 5-digit pricing (e.g., EURUSD 1.1000 vs 1.10005) and adjusts the Stop Loss and Take Profit calculations accordingly.
• Risk Management: Includes inputs for Stop Loss and Take Profit. If you set them to 0, the trade will run without hard exits (not recommended).
• Trade Limiter: The CountOpenTrades() function ensures the EA only opens one trade at a time per currency pair. It will not open a new trade until the previous one hits SL/TP or is manually closed.

Q&A: Quantitative Trading with MQL4

Q: Why do we use Shift 1 and Shift 2 instead of Shift 0?
A: Shift 0 represents the currently forming candle. The Stochastic values on Shift 0 fluctuate with every tick. A crossover might happen halfway through the candle duration but disappear by the time the candle closes. Using Shift 1 (the most recently closed candle) ensures the crossover is confirmed and final.

Q: How can I filter this strategy to only trade in the direction of the trend?
A: You can add a Moving Average filter. For example, add a condition in the OnTick function: double ma = iMA(NULL, 0, 200, ...);. Then, only execute a Buy signal if Close[1] > ma and only execute a Sell signal if Close[1] < ma.

Q: What is the Magic Number used for?
A: The Magic Number is a unique identifier assigned to orders opened by this specific EA. It allows the EA to distinguish its own trades from trades opened by you manually or by other EAs running on the same account.

Q: Can this EA handle ECN brokers?
A: The provided code uses standard OrderSend with SL and TP. Most modern MT4 bridges handle this fine. However, on some strict ECN brokers, you must send the order with 0 SL/TP first, get the ticket number, and then use OrderModify to add the SL/TP. The code provided works for 95% of standard retail brokers.