Expert Advisor Programming by Andrew R. Young

Working with Functions
int OpenBuyOrder(string argSymbol, double argLotSize, double argSlippage,
double argMagicNumber, string argComment = "Buy Order")
{
while(IsTradeContextBusy()) Sleep(10);
// Place Buy Order
int Ticket = OrderSend(argSymbol,OP_BUY,argLotSize,MarketInfo(argSymbol,MODE_ASK),
argSlippage,0,0,argComment,argMagicNumber,0,Green);
// Error Handling
if(Ticket == -1)
{
int ErrorCode = GetLastError();
string ErrDesc = ErrorDescription(ErrorCode);
string ErrAlert = StringConcatenate("Open Buy Order – Error ",
ErrorCode,": ",ErrDesc);
Alert(ErrAlert);
}
string ErrLog = StringConcatenate("Bid: ",MarketInfo(argSymbol,MODE_BID),
" Ask: ",MarketInfo(argSymbol,MODE_ASK)," Lots: ",argLotSize);
Print(ErrLog);
}
return(Ticket);
In the OrderSend() function, note that we've used the MarketInfo() function with the MODE_ASK
parameter, in place of the predefined Ask variable. This will retrieve the current Ask price for the
currency symbol indicated by argSymbol.
If the trade was not placed successfully, the error handling routine will be run. Otherwise the order
ticket will be returned to the calling function, or -1 if the order was not placed. The complete order
placement function for sell market orders is in Appendix D.
Pending Order Placement
To place pending orders, we'll need to pass parameters for the pending order price as well as the
order expiration time. The argPendingPrice and argExpiration arguments will be added to the
function.
We'll assume that the pending order price, as well as the stop loss and take profit, have been
calculated and verified prior to calling this function. The pending order placement functions will place
the stop loss and take profit with the pending order, so no separate order modification function is
required.
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