Expert Advisor Programming by Andrew R. Young

EXPERT ADVISOR PROGRAMMING
Margin Check
MetaTrader comes with functions that allow you to check the current free margin or stop out level
before placing an order. The stop out level is the percentage or amount of free margin below which
you will not be able to place orders. Manually checking the free margin or stop out level before
placing an order is not really necessary however, as an error will occur if you try to place an order
with too little margin.
A more useful idea would be to determine your own stop out level, and halt trading if the current
equity goes below that level. Let's start by declaring an external variable called MinimumEquity,
which is the minimum amount of equity required in our account before we can place an order.
We'll compare MinimumEquity to our current account equity. If the current equity is less than our
minimum equity, the order will not be placed, and an alert message will inform the user of the
condition. Let's assume we have an account balance of $10,000. If we lose more than 20% of that
equity, we do not want to place the order. Here is the code to check the minimum equity:
// External variables
extern int MinimumEquity = 8000;
// Order placement
if(AccountEquity() > MinimumEquity)
{
// Place order
}
else if(AccountEquity()