Expert Advisor Programming by Andrew R. Young

EXPERT ADVISOR PROGRAMMING
Here's another example using moving averages. We'll create a condition to open an order only when
the FastMA and the SlowMA have crossed within the last bar:
double FastMA = iMA(NULL,0,FastMAPeriod,0,0,0,0);
double SlowMA = iMA(NULL,0,SlowMAPeriod,0,0,0,0);
double LastFastMA = iMA(NULL,0,FastMAPeriod,0,0,0,1);
double LastSlowMA = iMA(NULL,0,SlowMAPeriod,0,0,0,1);
if(FastMA > SlowMA && LastFastMA = LastSlowMA
&& SellMarketCount(Symbol(),MagicNumber) == 0)
{
// Open sell order
}
In this example, we're comparing the relationship of two indicators to each other. LastFastMA and
LastSlowMA return the moving average values for the previous bar. If LastFastMA is less than (or
equal to) LastSlowMA, and FastMA is currently greater than SlowMA, then we know that the fast
moving average line has crossed above the slow moving average line within the last bar.
This provides a reliable trading signal, since we can limit our order placement to right after the cross
occurs. You can change the Shift value for the LastFastMA and LastSlowMA functions if you want
to increase the number of bars to look back when finding an indicator cross.
We've added the LastFastMA and LastSlowMA comparison to our buy and sell order conditions in
our expert advisor. We can now remove the BuyTicket and SellTicket check, since this method is
more reliable that checking a stored order ticket number. We also don't have to worry about orders
being placed well after the cross has occurred. See the expert advisor code in Appendix C to view all
of the changes.
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