Expert Advisor Programming by Andrew R. Young

EXPERT ADVISOR PROGRAMMING
We begin by including the file that has our functions in it, in this case IncludeExample.mqh. The
variable declarations and the contents of the init() function are the same as before. At the
beginning of the start() function, we use CalcLotSize() and VerifyLotSize() to to calculate
and verify our lot size.
In our buy and sell order blocks, we use CloseBuyOrder() and CloseSellOrder() to close the
opposite order. Our new orders are opened using OpenBuyOrder() or OpenSellOrder(). Before
calculating the stop loss and take profit, we check that the order was opened and that a StopLoss or
TakeProfit has been specified.
We retrieving the opening price of the order using OrderSelect() and OrderOpenPrice(). We then
calculate our stop loss using CalcBuyStopLoss() or CalcSellStopLoss(), and our take profit using
CalcBuyTakeProfit() or CalcSellTakeProfit().
We check to see if the stop loss or take profit is greater than 0, and use the functions
AdjustAboveStopLevel() and AdjustBelowStopLevel() to verify our stop loss and take profit
prices. Finally, we pass those prices to the AddOrderProfit() function, which adds the stop loss and
take profit to the order.
The EA above does exactly the same thing as the code starting on page 51, but is much easier to
read. By breaking the code into functions, we have de-cluttered our source code and made our EA
easier to manage. We will add a few more features to this expert advisor before the end of the book.
You can view the complete code in Appendix C.
The initial work in creating these functions will take some time, but it will save you time in the long
run, as you will more easily be able to prototype trading ideas and turn out working expert advisors
in a short amount of time.
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