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From: bobduff@world.std.com (Robert A Duff)
Subject: Re: Most efficient way to check for null string?
Date: 1997/06/21
Message-ID: <EC3ttx.I1o@world.std.com>#1/1
X-Deja-AN: 251477138
References: <5oe038$2d0$1@goanna.cs.rmit.edu.au>
 <EC3C0x.E68.0.-s@inmet.camb.inmet.com>
Organization: The World Public Access UNIX, Brookline, MA
Newsgroups: comp.lang.ada
Date: 1997-06-21T00:00:00+00:00
List-Id: <comp.lang.ada>


In article <EC3C0x.E68.0.-s@inmet.camb.inmet.com>,
Tucker Taft <stt@houdini.camb.inmet.com> wrote:
>...If you really want to
>shave cycles, the following will likely be the most efficient:
>
>     if Str'Last < Str'First then ...

Bletch.  That's the least readable of all, but Tucker's right that it
might be more efficient.  Tucker didn't say why.  It's because Ada
(foolishly, IMHO) allows Str's range to be something like
1_000 .. -1_000_000.  Which means that calculating the 'Length involves
a conditional jump in the general case.

- Bob