I need some help... This might seem pretty simple to some people, but I'm really have difficulty figuring this problem out.
I need to add two numbers on using the increment(1+) and decrement(1-) functions.. I have the logic for adding work however I need help printing NIL if the user enters a non numeric value.. Any ideas.. I'm not sure how to implement the arguement with two values. I also know I need to use numberp, but that only accepts one value..
I've tried (and (numberp n)(numberp m)) which is the correct logic, but when I add this to my function I get an error that says:
"Function called with two arguements, but wants exactly one"
Thanks in advance!