Expert Advisor Programming by Andrew R. Young

Tips and Tricks
• Illegal assignment used – This is usually in reference to an equal sign (=). Remember
that a single equal sign is for variable assignment, and two equal signs (==) is a comparison
operator. Correct the assignment operator to the appropriate comparison operator.
• Assignment expected – This is usually in reference to the "equal to" comparison operator
(==). You used two equal signs instead of one in a variable assignment. Correct the operator
to a single equal sign.
• Unbalanced right parenthesis – These usually occur in an if statement when using
nested parentheses. Go to the line indicated by the first error and insert a left parenthesis in
the appropriate place.
• Unbalanced left parenthesis – This is a tricky one. The error usually points to the end of
program line. Basically you forgot a right parenthesis somewhere. Double check the code you
recently edited and look for a missing right parenthesis. You may have to comment out lines
of code to locate the problem.
• Wrong parameters count – You have too few or too many arguments in a function.
Double check the function syntax in the MQL Reference and correct the arguments.
• Semicolon expected – You probably forgot to put a semicolon at the end of a line. Place a
semicolon at the end of the previous line. Note that a missing semi-colon may cause any of
the above errors as well, so be sure to place those semicolons!
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