Expert Advisor Programming by Andrew R. Young

EXPERT ADVISOR PROGRAMMING
// Calculate stop loss and take profit
if(StopLoss > 0) double BuyStopLoss = OpenPrice - (StopLoss * UsePoint);
if(TakeProfit > 0) double BuyTakeProfit = OpenPrice + (TakeProfit * UsePoint);
// Verify stop loss and take profit
if(BuyStopLoss > 0 && BuyStopLoss > LowerStopLevel)
{
BuyStopLoss = LowerStopLevel - MinStop;
}
if(BuyTakeProfit > 0 && BuyTakeProfit < UpperStopLevel)
{
BuyTakeProfit = UpperStopLevel + MinStop;
}
// Modify order
if(IsTradeContextBusy()) Sleep(10);
if(BuyStopLoss > 0 || BuyTakeProfit > 0)
{
bool TicketMod = OrderModify(BuyTicket,OpenPrice,BuyStopLoss,
BuyTakeProfit,0);
// Error handling
if(TicketMod == false)
{
ErrorCode = GetLastError();
ErrDesc = ErrorDescription(ErrorCode);
ErrAlert = StringConcatenate("Modify Buy Order - Error ",
ErrorCode,": ",ErrDesc);
Alert(ErrAlert);
}
}
}
ErrLog = StringConcatenate("Ask: ",Ask," Bid: ",Bid," Ticket: ",
BuyTicket," Stop: ",BuyStopLoss," Profit: ",BuyTakeProfit);
Print(ErrLog);
}
SellTicket = 0;
The remainder of our code contains the sell market order placement block, as well as the
PipPoint() and GetSlippage() functions. You can view the full code for this expert advisor in
Appendix B.
Note that we've added the IsTradeContextBusy() function prior to every trade operation. We want
to make sure that the trade thread is free before attempting to trade. We use the RefreshRates()
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