assignment versus comparison

Question

I'm trying to get my head straight about similarities and differences between VBA and JavaScript/PHP.

In the latter there's a strict distinction between assignment (using '=') and comparison (using '=='). I don't see any such distinction in my VBA sources.

Am I correct in concluding that in VBA I don't need to make the distinction and can just use '=' in both kinds of situations?

Thanks.

Answer 1

I don't work in PHP, but from what you wrote, I think a clarification is needed. In VBA, assignments cannot be embedded within other function calls... they must be done is a stand-alone statement (that is how come the equal sign can serve two purposes... how it is being used determines how it is implemented). The way you would write your PHP example wouls be like this...

r = "dog"

If Len(r) > 0 Then

  ' do something

End If

or, you could write the If test this way...

If r <> "" Then

but the Len method is faster in VBA (due to the way strings are stored in it). Oh, I guess I should explain Mike's example. In this statement...

r = "this" = "THIS"

the first equal sign is an assigment (because there is a variable on the left of it) and the second equal sign is a logical comparison operator because an assignment cannot take place from that position in the code statement.

Answer 2

 In VBA, assignments cannot be embedded within other function calls... they must be done is a stand-alone statement

That's the differentiator I was looking for.

Thanks.

Answer 3

So in PHP if I write

   if(r="dog")

   {  //do something },

this will always do something because PHP takes the condition as an assignment and so it's always true, but VBA can somehow tell (from context?) that that's not what's wanted:

  if r="dog" then

     'do something

  end if

Answer 4

Hi,

In VBA then the single = serves as both assignment and comparitor but is case sensitive in the latter case. This for example evaluates as FALSE

r = "this" = "THIS"