topic Re: What is the difference between 'assignment' and 'equality' operators in 3ds Max Programming Forum

What is the difference between 'assignment' and 'equality' operators

dvgbaokar — Thu, 30 Oct 2025 04:17:13 GMT

Learning max script with help of "Script help documentation"

In FAQ s came across this question

"What is the difference between 'assignment' and 'equality' operators'

While evaluating in listener and editor both codes give same result

not throwing any error in the first case when " if a = 0 " is written instead of " a ==0"

TYPICAL ERROR:

   a = 1
   if a = 0 then print "A is Zero!" else print "A is not Zero!"
   -- Type error: if-test requires BooleanClass, got: 0

CORRET CODE:

   a = 1
   if a == 0 then print "A is Zero!" else print "A is not Zero!"
   -->"A is not Zero!"

MartinBeh — Thu, 30 Oct 2025 08:44:06 GMT

1.) a = 0 is an assignment in MAXScript, i.e. "store the value 0 in the variable a"

2.) a == 0 is an equality comparison, i.e. "check whether a contains the value zero"

But you are right!

MAXScript no longer complains about

if a=0 then ( ... )

You can also simply write

0==false

and get "true" as result, without an error

Not sure when this was changed! It used to throw an error, but now it seems to do the same many other programming languages do:

It will use "0" as equivalent to "false"...

istan — Thu, 30 Oct 2025 12:48:02 GMT

Fortunately you must not write now (a === b) 😁