Quick question about input validation

Greetings all.

I'm making a program for college that creates a bush part fist angle drg from specified dims. I will be using dcls later on but for now im just trying to get my head around error handling and input validation.

(defun jm_dims () ;; Sets all of the user defined variables. Preset for testing!
 (setq jm_p0 (getpoint "\nPick a Point of Origin: "))
 (command "vslide" "BUSH3.sld")
 (initget 7)
 (setq jm_dima (getint "\nEnter Dimension A: "))
 (initget 7)
 (setq jm_dimb (getint "\nEnter Dimension B: "))
 (initget 7)
 (setq jm_dimc (getint "\nEnter Dimension C: "))
 (initget 7)
 [b](setq jm_dimd (getint "\nEnter Dimension D: "))[/b]
 (initget 7)
 [b](setq jm_dime (getint "\nEnter Dimension E: "))[/b]
 (initget 7)
 (setq jm_dimf (getint "\nEnter Dimension F: "))
 (initget 7)
 (setq jm_dimg (getint "\nEnter Dimension G: "))

)

The above is the function that gets all of the required info from the user. (no sh*t )

Whats anoying me is that I can't figure out how to go about making sure Dimension E

I.e. If dimd = 1000 and the user enters 1500 for dime it says "woa 'ang on, dime must be less than dimd... try again chap".

Noob question I know but the developers guide has been no help to me and I cant find anything I can adapt on this forum.

Cheers in advance.

ps heres the full prog so far.

;_______________________________
;
; James Morris
; Morgan Professional Services
; Programming Concepts Project
; Parametric Bush Program      
; JM_AUTOBUSH.LSP       
; 
;¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
(prompt "loading JM_AUTOBUSH.lsp... ") ;; displays to the user that the program is loading.
(defun jm_dims () ;; Sets all of the user defined variables. Preset for testing!
 (setq jm_p0 (getpoint "\nPick a Point of Origin: "))
 (command "vslide" "BUSH3.sld")
 (initget 7)
 (setq jm_dima (getint "\nEnter Dimension A: "))
 (initget 7)
 (setq jm_dimb (getint "\nEnter Dimension B: "))
 (initget 7)
 (setq jm_dimc (getint "\nEnter Dimension C: "))
 (initget 7)
 (setq jm_dimd (getint "\nEnter Dimension D: "))
 (initget 7)
 (setq jm_dime (getint "\nEnter Dimension E: "))
 (initget 7)
 (setq jm_dimf (getint "\nEnter Dimension F: "))
 (initget 7)
 (setq jm_dimg (getint "\nEnter Dimension G: "))
;  (setq ;; Picks point of origin and requests dimensions.
;
;    jm_dima 75
;    jm_dimb 100
;    jm_dimc 20
;    jm_dimd 200
;    jm_dime 50
;    jm_dimf 80
;    jm_dimg 100
;    jm_polywidth 0.25
;  )
)
(defun jm_loadlinetypes ()
 (setq jm_linelist '(("Center" . "acadiso.lin") ("Hidden" . "acadiso.lin")))
 (foreach lin jm_linelist
   (if (tblsearch "LTYPE" (car lin))
     (command ".-linetype" "_Load" (car lin) (cdr lin) "_Yes" "")
     (command ".-linetype" "_Load" (car lin) (cdr lin) "")
   )
 )
)
(defun jm_pointcalculations () ;; all of the refpoints are defined here.
 (setq  ;; 
; Descided this wasnt what I was after. The plan was to draw half
; then mirror along the centerline. I didn't like how it was
; looking so I binned it.
;
;    jm_p1 (getpoint "\nPick Point of origin: ")
;    jm_p2 (list (car jm_p1) (- (cadr jm_p1) (/ jm_dimd 2))) 
;    jm_p3 (list (+ (car jm_p2) jm_dima) (cadr jm_p2))
;    jm_p4 (list (car jm_p3) (cadr jm_p1))
;    jm_p5 (list (car jm_p3) (- (cadr jm_p1) (/ jm_dimg 2)))
;    jm_p6 (list (+ (car jm_p5) jm_dimb) (cadr jm_p5))
;    jm_p7 (list (car jm_p6) (cadr jm_p1))
;    jm_p8 (list (car jm_p7) (- (cadr jm_p1) (/ jm_dimf 2)))
;    jm_p9 (list (+ (car jm_p8) jm_dimc) (cadr jm_p8))
;    jm_p10 (list (car jm_p9) (cadr jm_p1))
;    jm_p11 (list (car jm_p1) (- (cadr jm_p1) (/ jm_dime 2)))
;    jm_p12 (list (car jm_p10) (- (cadr jm_p1) (/ jm_dime 2)))
;    jm_p13 (list (+ (car jm_p10) (/ jm_dimd 2)) (cadr jm_p10))
;    jm_p14 (list (- (car jm_p1) jm_dimd) (cadr jm_p1))
;    jm_p15 (list (- (car jm_p14) jm_dimd) (cadr jm_p1))

;    jm_p0 (getpoint "\nPick a Point of Origin: ")
   jm_p1 (list (car jm_p0) (- (cadr jm_p0) (/ jm_dimd 2)))
   jm_p2 (list (+ (car jm_p1) jm_dima) (cadr jm_p1))
   jm_p3 (list (car jm_p2) (+ (cadr jm_p2) jm_dimd))
   jm_p4 (list (car jm_p1) (cadr jm_p3))
   jm_p5 (list (car jm_p2) (- (cadr jm_p0) (/ jm_dime 2)))
   jm_p6 (list (+ (car jm_p5) jm_dimb) (cadr jm_p5))
   jm_p7 (list (car jm_p6) (+ (cadr jm_p5) jm_dime))
   jm_p8 (list (car jm_p5) (cadr jm_p7))
   jm_p9 (list (car jm_p6) (- (cadr jm_p0) (/ jm_dimf 2)))
   jm_p10 (list (+ (car jm_p9) jm_dimc) (cadr jm_p9))
   jm_p11 (list (car jm_p10) (+ (cadr jm_p9) jm_dimf))
   jm_p12 (list (car jm_p9) (cadr jm_p11))
   jm_p13 (list (car jm_p1) (- (cadr jm_p0) (/ jm_dimg 2)))
   jm_p14 (list (car jm_p10) (cadr jm_p13))
   jm_p15 (list (car jm_p1) (+ (cadr jm_p0) (/ jm_dimg 2)))
   jm_p16 (list (car jm_p10) (cadr jm_p15))
   jm_p17 (list (- (car jm_p0) (* jm_dimd 2)) (cadr jm_p0))
   jm_p18 (list (- (car jm_p0) jm_dimd) (cadr jm_p0))
   jm_p19 (list (+ (car jm_p10) (/ jm_dimd 2)) (cadr jm_p0))
 )
)
(defun jm_drawthe****** ()
; I've binned these for the same reason as the points above
;
;  (command "pline" jm_p1 jm_p2 jm_p3 jm_p4)
;  (command)
;  (command "pline" jm_p5 jm_p6 jm_p7)
;  (command)
;  (command "pline" jm_p8 jm_p9 jm_p10)
;  (command)
;  (command "line" jm_p11 jm_p12)
;  (command)
;  (command "Circle" jm_p14 "d" jm_dimd)
;  (command)
;  (command "Circle" jm_p14 "d" jm_dime)
;  (command)
;  (command "Circle" jm_p14 "d" jm_dimf)
;  (command)
;  (command "Circle" jm_p14 "d" jm_dimg)
;  (command)
;  (command "line" jm_p15 jm_p13)
;  (command)
 (command "-layer" "Make" "PART" "Color" "Green" "" "") (command) ;; sets the layer prior to drawing the line.
;  (command "pline" jm_p1 "w" jm_polywidth "" jm_p2 jm_p3 jm_p4 "c") (command) ;; polylines look ****
;  (command "pline" jm_p5 "w" jm_polywidth "" jm_p6 jm_p7 jm_p8) (command)
;  (command "pline" jm_p9 "w" jm_polywidth "" jm_p10 jm_p11 jm_p12) (command)
 (command "line" jm_p1 jm_p2 jm_p3 jm_p4 "c") (command)
 (command "line" jm_p5 jm_p6 jm_p7 jm_p8) (command)
 (command "line" jm_p9 jm_p10 jm_p11 jm_p12) (command)
 (command "circle" jm_p18 "d" jm_dimd) (command)
 (command "circle" jm_p18 "d" jm_dime) (command)
 (command "circle" jm_p18 "d" jm_dimf) (command)
 (command "circle" jm_p18 "d" jm_dimg) (command)
 (command "-layer" "Make" "HIDDEN" "Color" "Blue" "" "Ltype" "Hidden" "" "") (command)
 (command "line" jm_p13 jm_p14) (command)
 (command "line" jm_p15 jm_p16) (command)
 (command "-layer" "Make" "CENTER" "Color" "Red" "" "Ltype" "Center" "" "") (command)
 (command "line" jm_p17 jm_p19) (command)
 (command "-layer" "Set" "0" "") (command)
 (command "regenall") (command)
 (command "Zoom" "Extents") (command)
 (princ)
)
(defun c:jm_start ()
 (setq ;;
   jm_oldosmode (getvar "osmode")
   jm_oldcmdecho (getvar "cmdecho")
 )
 (setvar "osmode" 0)
 (setvar "cmdecho" 0)
 (jm_dims)
 (jm_pointcalculations)
 (jm_loadlinetypes)
 (jm_drawthe******)
 (jm_debug) ;; activated when wanting to print all variables and quantities to commandline.
 (setvar "osmode" jm_oldosmode)
 (princ)
 (setvar "cmdecho" jm_oldcmdecho)
 (princ)
)
(defun jm_debug () ; Debugging mode. lists all variables and their current values
 (princ "\n") (princ "\nUser Defined Variables...")
 (princ "\njm_dima = ") (princ jm_dima) (princ "\njm_dimb = ") (princ jm_dimb)
 (princ "\njm_dimc = ") (princ jm_dimc) (princ "\njm_dimd = ") (princ jm_dimd)
 (princ "\njm_dime = ") (princ jm_dime) (princ "\njm_dimf = ") (princ jm_dimf)
 (princ "\njm_dimg = ") (princ jm_dimg) (princ "\njm_polywidth = ") (princ jm_polywidth)
 (princ "\n") (princ "\nCalculated Points...")
 (princ "\njm_p0 = ") (princ jm_p0) (princ "\njm_p1 = ") (princ jm_p1)
 (princ "\njm_p2 = ") (princ jm_p2) (princ "\njm_p3 = ") (princ jm_p3)
 (princ "\njm_p4 = ") (princ jm_p4) (princ "\njm_p5 = ") (princ jm_p5)
 (princ "\njm_p6 = ") (princ jm_p6) (princ "\njm_p7 = ") (princ jm_p7)
 (princ "\njm_p8 = ") (princ jm_p8) (princ "\njm_p9 = ") (princ jm_p9)
 (princ "\njm_p10 = ") (princ jm_p10) (princ "\njm_p11 = ") (princ jm_p11)
 (princ "\njm_p12 = ") (princ jm_p12) (princ "\njm_p13 = ") (princ jm_p13)
 (princ "\njm_p14 = ") (princ jm_p14) (princ "\njm_p15 = ") (princ jm_p15)
 (princ "\njm_p16 = ") (princ jm_p16) (princ "\njm_p17 = ") (princ jm_p17)
 (princ "\njm_p18 = ") (princ jm_p18) (princ "\njm_p19 = ") (princ jm_p19)
 (princ "\n")
)
(prompt "\n...loaded ")
(terpri)
(prin1)

You'll need something like this:

[b][color=BLACK]([/color][/b]initget 7[b][color=BLACK])[/color][/b]
[b][color=BLACK]([/color][/b]setq jm_dimd [b][color=FUCHSIA]([/color][/b]getint [color=#2f4f4f]"\nEnter Dimension D: "[/color][b][color=FUCHSIA])[/color][/b][b][color=BLACK])[/color][/b]
[b][color=BLACK]([/color][/b]while [b][color=FUCHSIA]([/color][/b]or [b][color=NAVY]([/color][/b]not jm_dime[b][color=NAVY])[/color][/b]
          [b][color=NAVY]([/color][/b]> jm_dime jm_dimd[b][color=NAVY])[/color][/b][b][color=FUCHSIA])[/color][/b]
      [b][color=FUCHSIA]([/color][/b]initget 7[b][color=FUCHSIA])[/color][/b]
      [b][color=FUCHSIA]([/color][/b]setq jm_dime [b][color=NAVY]([/color][/b]getint [color=#2f4f4f]"\nEnter Dimension E: "[/color][b][color=NAVY])[/color][/b][b][color=FUCHSIA])[/color][/b][b][color=BLACK])[/color][/b]

-David

hehe much appreciated chap. I was trying while loops with little success but putting an "or" in there didn't cross my mind.

Cheers,

James

I think I would use an if or cond phrase within a while statement, i.e.

(while (dima<dimb)
  (setq dimb (getint "Input: "))
  (cond (dima<dimb)
    (princ "wrong input")
  )
)

I think, maybe wrong, still learning...