Re: Parameter Modes, In In Out and Out

["DuckE" <nospam_steved94@home.com>]

"i.a.mcleod" <i.a.mcleod@ntlworld.com> wrote in message
news:Zmt56.57012$ca6.937797@news6-win.server.ntlworld.com...
> What is the difference between In Out and Out parameters according to the
> way compilers handle these.  I can't see any difference.  An out parameter
> is still taken in.  I am confused by this anyone help?
>
>

I'm not sure whether all compilers handle this the same, but with the
compiler I use most frequently:

A parameter that is passed as an "In Out" will have a constraint check on
entry to the procedure and a parameter passed as "Out" will not.

This became obvious to me when translating Pascal code to Ada 95.  In Pascal
it is common to pass an uninitialized variable as a "VAR" parameter to a
procedure.  In Pascal this did not result in an exception.  Using an Ada "In
Out" sometimes causes a constraint error exception and using Adas' "Out"
does not.


SteveD