[LISP] How to convert exact string to number?

[iBlachu]

I want to exactly convert a number in a string to a number so that it has the same rounding.

An example that doesn't work for me.

(cvunit 35.5 "KG" "OZ")

1252.23

(rtos (cvunit 35.5 "KG" "OZ") 2 3)

"1252.226"

Now how do I convert the string from this "1252.226" calculation to a real number?

Such action

(atof (rtos (cvunit 35.5 "KG" "OZ") 2 3))

returns 1252.23, not 1252.226!

[john.uhden]

@iBlachu 

Ii's not that AutoCAD isn't converting correctly.  It's just how it displays the result.

I think I use (read) more than (atof)...

Command: (read "1252.226" )
1252.23

Command: (rtos (read "1252.226") 2 6)
"1252.226000"

Command: dimzin ;; Look it up - controls display of leading and trailing zeroes.

Enter new value for DIMZIN <0>: 8

Command: (rtos (read "1252.226") 2 6)
"1252.226"

[iBlachu]

Unfortunately, that's not what I'm talking about.

Maybe otherwise, why (atof "1252.226") returns 1252.23 and not 1252.226?

How to change this rounding?

Or even differently, how to replace the string "1252.226" with the number 1252.226?

[paullimapa]

as others replied, it's actually there but you don't see it

try: (rtos (atof"1252.226") 2 6)

returns: "1252.226000"

atof precision - Autodesk Community - AutoCAD

[iBlachu]

I need to have a valid (unrounded) value of 1252.226 in a numeric variable.

How to convert it without rounding?

[paullimapa]

since you want a numeric value I just showed up how...but regardless there has to be a rounding value but that's for you to determine and should not be left as an unknown

[iBlachu]

So in this case I would like to specify as 3 decimal places.

rtos works and converts to a string.
And I need exactly the same value but as a number.

[paullimapa]

again as others have replied to you:

(read(rtos (atof"1252.226") 2 3))

[iBlachu]

Unfortunately not.

[iBlachu]

The whole problem boils down to this

(setq a 1252.226)

!a

1252.23

[paullimapa · Accepted solution]

just run the following tests and you'll believe...

Command: (= (setq a(read(rtos (atof"1252.226") 2 3))) 1252.23)
nil

Command: (= (setq a(read(rtos (atof"1252.226") 2 3))) 1252.226)
T

Command: !a
1252.23

Command: (= a 1252.226)
T

Command: (= a 1252.23)

nil

[iBlachu]

OK, but how do I display it as a number?

[paullimapa]

Just display it as a string which you’ll have to covert it to anyways 

[iBlachu]

It's an idea. Thanks for support.

[paullimapa]

glad to have helped....cheers!!!

[Sea-Haven]

I think you were missing the fact that acad holds the number as lots of decimals but various variables control how it is displayed.

(setq num 123.456789)
123.456789
: !num
123.456789
: (rtos num 2 3)
"123.457"
(atof (rtos num 2 3))
123.457
: (atof (rtos num 2 2))
123.46
(atof (rtos num 2 5))
123.45679

Correct use of rounding functions will convert the number to what you want as a number.

[iBlachu]

It doesn't work in some cases.
Check the case with the number 1252.226

[ВeekeeCZ]

So it seems that LISP shows you just 6 valid digits of a real number - while internally holding the maximum precision possible (by definition).

[kpblc2000]

Hope this code could helps

(defun t1 (/ value sysvars)
  (setq value   125.226
        sysvars (mapcar (function (lambda (x)
                                    (cons x (getvar x))
                                  ) ;_ end of lambda
                        ) ;_ end of function
                        '("dimzin" "luprec")
                ) ;_ end of mapcar
  ) ;_ end of setq
  (foreach luprec '(0 1 2 4 8)
    (setvar "luprec" luprec)
    (foreach dimzin '(0 1 2 3 4 8 12)
      (setvar "dimzin" dimzin)
      (princ (strcat "\nluprec = "
                     (itoa luprec)
                     "; dimzin = "
                     (itoa dimzin)
                     "; (rtos value 2) = "
                     (rtos value 2)
             ) ;_ end of strcat
      ) ;_ end of princ
    ) ;_ end of foreach
  ) ;_ end of foreach
  (foreach item sysvars
    (setvar (car item) (cdr item))
  ) ;_ end of foreach
  (princ)
) ;_ end of defun

And results will be like

_$ (t1)

luprec = 0; dimzin = 0; (rtos value 2) = 125
luprec = 0; dimzin = 1; (rtos value 2) = 125
luprec = 0; dimzin = 2; (rtos value 2) = 125
luprec = 0; dimzin = 3; (rtos value 2) = 125
luprec = 0; dimzin = 4; (rtos value 2) = 125
luprec = 0; dimzin = 8; (rtos value 2) = 125
luprec = 0; dimzin = 12; (rtos value 2) = 125
luprec = 1; dimzin = 0; (rtos value 2) = 125.2
luprec = 1; dimzin = 1; (rtos value 2) = 125.2
luprec = 1; dimzin = 2; (rtos value 2) = 125.2
luprec = 1; dimzin = 3; (rtos value 2) = 125.2
luprec = 1; dimzin = 4; (rtos value 2) = 125.2
luprec = 1; dimzin = 8; (rtos value 2) = 125.2
luprec = 1; dimzin = 12; (rtos value 2) = 125.2
luprec = 2; dimzin = 0; (rtos value 2) = 125.23
luprec = 2; dimzin = 1; (rtos value 2) = 125.23
luprec = 2; dimzin = 2; (rtos value 2) = 125.23
luprec = 2; dimzin = 3; (rtos value 2) = 125.23
luprec = 2; dimzin = 4; (rtos value 2) = 125.23
luprec = 2; dimzin = 8; (rtos value 2) = 125.23
luprec = 2; dimzin = 12; (rtos value 2) = 125.23
luprec = 4; dimzin = 0; (rtos value 2) = 125.2260
luprec = 4; dimzin = 1; (rtos value 2) = 125.2260
luprec = 4; dimzin = 2; (rtos value 2) = 125.2260
luprec = 4; dimzin = 3; (rtos value 2) = 125.2260
luprec = 4; dimzin = 4; (rtos value 2) = 125.2260
luprec = 4; dimzin = 8; (rtos value 2) = 125.226
luprec = 4; dimzin = 12; (rtos value 2) = 125.226
luprec = 8; dimzin = 0; (rtos value 2) = 125.22600000
luprec = 8; dimzin = 1; (rtos value 2) = 125.22600000
luprec = 8; dimzin = 2; (rtos value 2) = 125.22600000
luprec = 8; dimzin = 3; (rtos value 2) = 125.22600000
luprec = 8; dimzin = 4; (rtos value 2) = 125.22600000
luprec = 8; dimzin = 8; (rtos value 2) = 125.226
luprec = 8; dimzin = 12; (rtos value 2) = 125.226

[iBlachu]

Yes, but it's not about displaying the number as a string because it works through rtos, but about displaying the number as a number and here is the problem with this rounding. Your modified example below.

(defun t1 (/ value sysvars)
  (setq value   1252.226
        sysvars (mapcar (function (lambda (x)
                                    (cons x (getvar x))
                                  ) ;_ end of lambda
                        ) ;_ end of function
                        '("dimzin" "luprec")
                ) ;_ end of mapcar
  ) ;_ end of setq
  (foreach luprec '(0 1 2 4 8)
    (setvar "luprec" luprec)
    (foreach dimzin '(0 1 2 3 4 8 12)
      (setvar "dimzin" dimzin)
      (princ (strcat "\nluprec = "
                     (itoa luprec)
                     "; dimzin = "
                     (itoa dimzin)
                     "; (rtos value 2) = "
                     (rtos value 2)
             ) ;_ end of strcat
      ) ;_ end of princ


	  (print value)


    ) ;_ end of foreach
  ) ;_ end of foreach
  (foreach item sysvars
    (setvar (car item) (cdr item))
  ) ;_ end of foreach
  (princ)
) ;_ end of defun