error when adding variables

I am trying to get this LISP routine going and I am having an issue adding two variables together. When I run the program it returns

 ; error: bad argument type: numberp: nil 

here is the code segment in question

fa1    (+ fa1 inc)  
fa2    (+ fa2 inc) 

fa1, fa2, and inc are all supposed to be defined as integers and for some reason i keep getting that error and i dont understand why. Basically what is supposed to happen is fa1 gets define as (arbitrarily) 5 and fa2 will be 6, with inc being, say, 7. so basically fa1 and fa2 are both getting "incremented" by 7. Everything else seems to be going smoothly but i cant manage to get this small part to work. Any help is appreciated. Thanks

The error that you are returning seems that there is a variable in your coding that is perhaps defined incorrectly - i.e. as possibly a string.

The code that you have posted seems to be correct:

(setq fa1 (+ fa1 inc)
       fa2 (+ fa2 inc)
) ; end setq

But if you could post the rest of the LISP you are working on, there may be an error elsewhere.

@Lee Mac Thanks for the input, here's the rest of the code

 (setq ename  	(ssname ss index)
  index  	(1+ index)
         Fass  	(getattval ename "FIBER-ASS")
)
               (setq Fspl 	(splstr Fass "-")
		inc	(last Fspl)
		inc	(atoi inc)
		fa1	(car fspl)
		fa2	(last fspl)
		fa1	(+ fa1 inc)
		fa2	(+ fa2 inc)
		fa1 	(itoa fa1)
		fa2	(itoa fa2)
		Fincd	(strcat fa1 "-" fa2)

I am not sure of the functions "splstr" and "getattval" but maybe I do not know enough...

This code:

(setq fa1 (+ fa1 inc)

will give you an error if you haven't set fa1 to some value; fa1 is 'nil initially if not set to something, you can't add an increment to nil and thus an error.

Yop probably want to set fa1 to 0 initially?

ahh good point Carl.

But what are the "getattval" and "splstr" ? Do you know?

Don't know, most likely "defuns" (code not shown) that perform tasks of 'getting attribute values' & 'splitting a string'

What does the splstr function do to the Fass variable when it is passed through it? Does it split the string and retun it as a list of strings?

eg (splstr "100-2-5" "-") returns ("100" "2" "5")

Try

 (setq ename  	(ssname ss index)
  index  	(1+ index)
         Fass  	(getattval ename "FIBER-ASS")
)
               (setq Fspl 	(splstr Fass "-")
		inc	(last Fspl)
		inc	(atoi inc)
		fa1	[color="Red"](atoi [/color](car fspl)[color="red"])[/color] ;covert to integer
		fa2	[color="red"](atoi [/color](last fspl)[color="red"])[/color];covert to integer

		fa1	(+ fa1 inc)
		fa2	(+ fa2 inc)
		fa1 	(itoa fa1)
		fa2	(itoa fa2)
		Fincd	(strcat fa1 "-" fa2)

Jammie

getattval gets an attribute value and splstr splits a string based on, in this case, a hyphen and creates a list.

@CarlB Is the line fa1 (car fspl) not sufficient enough to properly assign a value to the variable in order to perform the math?

@Jammie that seems to work. Well, I mean its returning the correct value now. I just cant manage to get the rest of the routine to work . Anyways, thanks guys

Does (car faspl) return a number? If 'faspl' is a string then (car faspl) wil generate an error. After running the code and it 'errors', check what the value of faspl & fa1 are (and if OK keep checking...)

I think its probably a string

on a seemingly random note. is there a way to write

if (0
 in lisp?

(if
  (and
     (> x 0)
     (< x 10)
   )
)

shorter (almost exactly as Stephen posted):

(if (

It's often missed that lisp allows more than 2 items in an equality/inequality. For example this is legal

(= 1 2 3 4 5) -> nil

( T

Nice one Carl.... i must admit, I didn't realise that more than one item can be used in an equality/inequality - thanks.

Yes, I suppose that what my problem as well. Thanks guys