Re: struct inheritance

From:

"Neill" <noreply@mail.com>

Newsgroups:

comp.lang.c++

Date:

Sat, 14 Feb 2009 06:38:47 +0100

Message-ID:

<JNsll.252$qy7.64@newsfe30.ams2>

"Ian Collins" <ian-news@hotmail.com> wrote in message
news:6vmulaFksu50U7@mid.individual.net...

Neill wrote:

"Ian Collins" <ian-news@hotmail.com> wrote in message
news:6vmsdlFksu50U5@mid.individual.net...

Neill wrote:

The output is different than when writing:

NumExp* prog = new NumExp(10);

Uhm, the program that you posted has no output at all. Apparently, now
you
are talking about some program that you did not post. Since my crystal
ball
is currently in repair, I have no idea what you are talking about.

Srry, I mean, debugger is giving different results:

with: NumExp* prog = new NumExp(10);

prog --> some address
|_ Exp_ --> {...}
|_ num --> 10

with: Exp prog = new NumExp(10);

prog --> only some address but I would like to get same result
as above

Why? The second expression wouldn't compile. What are you really
testing?

The second expression compiles just fine over here with Visual Studio
.NET 2003 so I'm all confused.. Note that: typedef Exp_* Exp;

One good reason not to use pointless typedefs!

I would like to get same result with 2nd expression as with 1st but
something is wrong with this code and I don't know what.

Yes but why do you want to get the same result?

What is the significance of the value?

My intention was to inherit several different struct's from Exp_ so I could
treat them all the same. I was confused because the debugger is using static
type information.

NumExp* test = new NumExp(10);
Exp prog = test;

Debug information for test and prog is different.

Best regards