Expert Advisor Programming by Andrew R. Young

EXPERT ADVISOR PROGRAMMING
Updating the Expert Advisor
Let's modify the start() function of our moving average cross expert advisor to reflect the new
functions we have created. First, we will check to see if there are any buy orders open before we
open more. Instead of closing a single sell order, we will simply use the function to close all sell
orders. This method does not require us to use an order ticket.
// Buy Order
if(FastMA > SlowMA && BuyTicket == 0 && BuyMarketCount(Symbol(),MagicNumber) == 0)
{
if(SellMarketCount(Symbol(),MagicNumber) > 0)
{
CloseAllSellOrders(Symbol(),MagicNumber,Slippage);
}
SellTicket = 0;
}
BuyTicket = OpenBuyOrder(Symbol(),LotSize,UseSlippage,MagicNumber);
We used the function BuyMarketCount() that we defined on page 84 to return the number of buy
orders currently open. We will keep the BuyTicket check in, so that only alternating buy/sell orders
are opened.
The function CloseAllSellOrders() closes any sell orders that are open. We check
SellMarketCount() first to see if there are any sell orders to close. This function does not require
an order ticket, unlike the CloseSellOrder() function in chapter 4. It is recommended you use this
method for closing out opposite orders in your EA, as it is more robust.
The rest of the buy order placement code is the same as before. The corresponding sell order
placement code is below:
// Sell Order
if(FastMA < SlowMA && SellTicket == 0 && SellMarketCount(Symbol(),MagicNumber) == 0)
{
if(BuyMarketCount(Symbol(),MagicNumber) > 0)
{
CloseAllBuyOrders(Symbol(),MagicNumber,Slippage);
}
BuyTicket = 0;
}
SellTicket = OpenSellOrder(Symbol(),LotSize,UseSlippage,MagicNumber);
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