Re: Are unsigned integers necessary?

From:
"Leigh Johnston" <leigh@i42.co.uk>
Newsgroups:
comp.lang.c++
Date:
Fri, 16 Apr 2010 13:04:47 +0100
Message-ID:
<bNCdnR0xo_fHz1XWnZ2dnUVZ7qSdnZ2d@giganews.com>
"DaveB" <DBurns@usenet.net> wrote in message
news:jjYxn.58661$vC3.11369@newsfe04.iad...

"Leigh Johnston" <leigh@i42.co.uk> wrote in message
news:ZLadnVpFLpup3VXWnZ2dnUVZ8mydnZ2d@giganews.com...

Yes.


That there is Java and that it does not have them indicates NO. The
question, then, becomes about what the tradeoffs are. Maybe in a VM
environment the elimination of unsigned integers is easier to accept?


"Yes" was the answer to your post's subject question within the context of
C++. C++ already has unsigned integral types which will not be removed from
the language. There exists much code which uses unsigned integral types
including libraries and the C++ standard library so avoiding the use of
unsigned integral types when writing new code is not really possible.

The following is correct:

std::vector<int> v;
typedef std::vector<int>::size_type index;
....
for (index i = 0; i != v.size(); ++i)
{
  /* do stuff with v[i] */
}

Whilst the following is incorrect:

std::vector<int> v;
....
for (int i = 0; i != v.size(); ++i)
{
  /* do stuff with v[i] */
}

Use the right tool (type) for the job.

If you use the incorrect form you have an unnecessary signed/unsigned
conversion and although this may not actually cause any runtime problems for
this particular use-case you will at the very least get a compiler warning
which is a clue to its incorrectness.

/Leigh

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