Re: Most efficient way to check for null string?

[bobduff@world.std.com (Robert A Duff)]

In article <5oe038$2d0$1@goanna.cs.rmit.edu.au>,
Dale Stanbrough  <dale@goanna.cs.rmit.EDU.AU> wrote:
>I think the following are both equally readable, so which is likely 
>to be more efficient?
>
>	if Str = "" then
>	
>	if Str'Length = 0 then

I find the first slightly more readable.  I suspect they're very close
to the same efficiency.  I suspect that the second is at least as
efficient as the first (i.e. I would be surprised if a compiler did
worse on #2, but I would not be surprised if they were equal, or maybe
#2 slightly better).

The only sensible way to answer this question is to measure it.

It's quite easy to write a compiler where #1 is as efficient as #2.  If
a given compiler doesn't do that, I take it as an indication that its
customers don't care about this sort of thing.

- Bob