Re: Function f(lb,x,ub); equivalent to min(ub,max(lb,x)); ?

From:
David Wilkinson <no-reply@effisols.com>
Newsgroups:
microsoft.public.vc.mfc
Date:
Tue, 27 Feb 2007 05:15:48 -0500
Message-ID:
<edIgxglWHHA.1208@TK2MSFTNGP03.phx.gbl>
Harvey wrote:

On Feb 25, 11:57 pm, "Harvey" <harve...@juno.com> wrote:

Is there a (mfc) library function like f(lb,x,ub); that will return
the value of x if it is in range, else the bound x exceeded? It would
be equivalent to min(ub,max(lb,x)); but faster and not a macro? I
think I would use it a lot. :)
TIA,
Harvey


Final version:

template <typename T>
T Clamp( T lower, T x, T upper )
{
  if ( lower > x )
    return lower;
  if ( x > upper )
    return upper;
  return x;
}

I used > for both rather than < so that the flow would follow the
input args.
Thanks to all who commented.
Harvey


Harvey:

Not to beat a dead horse, but I would still follow what the standard
library does for min() and max(): use < only and const T&.

The reason to use < is because that is what many standard library
algorithms (like std::sort()) require to be defined. If you use > you
are placing a requirement on your class that is not required by the
standard library.

The reason to use const T& is that it will be much more efficient for a
complex type, particularly one that requires memory allocation in the
copy constructor. I would need detailed evidence that using T is more
efficient for simple types, and even if it was it would be extremely
unusual for it to really matter.

The standard library folks must have thought about these things before
they defined and implemented min() and max() the way they did.

David Wilkinson

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