Expert Advisor Programming by Andrew R. Young

Working with Functions
First, we'll check to see if a valid stop loss level has been passed along with the function. If the
argStopLoss argument is 0, then we return a value of 0 to the calling function, indicating that no
stop loss was specified.
Next, we calculate the stop loss by subtracting the stop loss in pips from the order opening price. We
multiply argStopLoss by PipPoint() to calculate the fractional value, and subtract that from
argOpenPrice. We will use either the Bid or Ask price (for market orders) or the intended pending
order price.
Note that we do not check the stop level or otherwise verify that the stop loss is valid. We will use
another set of functions to verify or adjust the stop loss price as necessary. You could, of course,
easily modify this function to verify the stop loss price, display an error message, or automatically
adjust the price.
Here is the function to calculate a buy take profit in pips:
double CalcBuyTakeProfit(string argSymbol, int argTakeProfit, double argOpenPrice)
{
if(argTakeProfit == 0) return(0);
double BuyTakeProfit = OpenPrice + (argTakeProfit * PipPoint(argSymbol));
return(BuyTakeProfit);
}
The functions for calculating stop loss and take profit for sell orders are listed in Appendix D. Note
that the function for calculating sell stop loss is nearly identical to the one above for calculating the
buy take profit, and likewise for buy stop loss and sell take profit.
Stop Level Verification
We're going to create two sets of functions to calculate and verify stop levels. The first will simply
calculate the stop level above or below a specified price, and return a boolean value indicating
whether the indicated price is inside or outside the stop level. A second set of functions will
automatically adjust a price so that it is outside the stop level, plus or minus a specified number of
pips.
The following function verifies whether a price is above the upper stop level (the order opening price
plus the stop level). If so, the function returns true, otherwise false:
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