Re: Base Class Reference [modified] - C / C++ / MFC Discussion Boards

kakan14-Jun-06 21:45

14-Jun-06 21:45

Hi again.
The person that gave you a 1 must have missed the "joke" symbol of your post, or is totally lacking all sense of humor. Frown | :(

Again, it wasn't me, truly. I really appreciated your twist. Big Grin | :-D

Re: OT

toxcct14-Jun-06 21:52

toxcct

14-Jun-06 21:52

anyway, i don't mind Wink | ;)

and i trust you if you say it wasn't you Rose | [Rose]

TOXCCT >>> GEII power

[VisualCalc 3.0 updated ][Flags Beginner's Guide new! ]

Re: OT

ThatsAlok14-Jun-06 19:30

ThatsAlok

14-Jun-06 19:30

kakan wrote:
Can't give you my 5 this time. Last time I was voted down for giving you a 5.

Sorry i voted you down for not giving Five Smile | :)

sorry!

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

cheers,
Alok Gupta
VC Forum Q&A :- I/ IV
Support CRY- Child Relief and You

Re: OT

kakan14-Jun-06 20:47

kakan

14-Jun-06 20:47

That's OK, I'm getting used to it. Laugh | :laugh:

Re: OT

ThatsAlok14-Jun-06 19:43

ThatsAlok

14-Jun-06 19:43

kakan wrote:
Can't give you my 5 this time. Last time I was voted down for giving you a 5.

Sorry In naughtyness i given you one.. now you have two option get two five (one for this and one free) from me or vote one for this message.. choice is yours Smile | :)

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

cheers,
Alok Gupta
VC Forum Q&A :- I/ IV
Support CRY- Child Relief and You

Re: OT

kakan14-Jun-06 21:16

kakan

14-Jun-06 21:16

Is it just me, or is this thread becoming a bit complex to follow? Confused | :confused:

To be honest, I don't really care about getting fives.
I'm more interested about the original subject.

IMO, a lot of the (mostly the vaguest) questions could be avoided if the poster learnt to use the debugger. Not to mention how much faster the problem would be solved.
(Everyone here knows it takes time to get an answer through a forum).

I totally agree with Cedrik here. Which is at reason I gave him my 5 for his two responses, telling the poster to learn how to use the debugger.
Kakan

Base Class Reference

Sarath C14-Jun-06 0:25

Sarath C

14-Jun-06 0:25

class CBase
{

};

class CDerived: public CBase
{
};

int main()
{
	CDerived d;
	CBase& b = d;
}

it was quite new information ( i haven't tried yet) that a base class can refer a derived class object. Could you pls explain the what is the difference with using a base class pointer?

Sa^Rath.

"Don't Do Different things... Do Things Differently..."

Understanding State Pattern in C++

Re: Base Class Reference [modified]

_AnsHUMAN_ 14-Jun-06 0:38

_AnsHUMAN_

14-Jun-06 0:38

A reference is treated like a constant pointer.
The big difference between pointers and references is that you must use an explicit operator-the * operator-to dereference a pointer, but you don't use an operator to dereference a reference.
In other words, once you bind a reference to refer to an object, you cannot rebind it to refer to a different object.
Now if you want to assign another derived class object to b you just can't.

Somethings seem HARD to do, until we know how to do them.
Wink | ;-)

_AnShUmAn_

-- modified at 7:31 Wednesday 14th June, 2006

Re: Base Class Reference

toxcct14-Jun-06 1:27

toxcct

14-Jun-06 1:27

_AnShUmAn_ wrote:
A reference is a constant pointer.

false.
it's a dereferenced pointer, but not const at all.

TOXCCT >>> GEII power

[VisualCalc 3.0 updated ][Flags Beginner's Guide new! ]

Re: Base Class Reference

_AnsHUMAN_ 14-Jun-06 1:33

_AnsHUMAN_

14-Jun-06 1:33

I was waiting for that.
:->Made the correction.

Somethings seem HARD to do, until we know how to do them.
Wink | ;-)

_AnShUmAn_

Re: Base Class Reference

toxcct14-Jun-06 1:36

toxcct

14-Jun-06 1:36

_AnShUmAn_ wrote:
Made the correction.

TOXCCT >>> GEII power

[VisualCalc 3.0 updated ][Flags Beginner's Guide new! ]

Re: Base Class Reference

sunit514-Jun-06 0:41

sunit5

14-Jun-06 0:41

u can consider Reference as const pointer

never say die

Re: Base Class Reference

John R. Shaw14-Jun-06 1:00

John R. Shaw

14-Jun-06 1:00

Where are you guys coming up with this stuff? If a reference was a constant pointer then you would need to use the ‘->’ operator instead of the ‘.’ Operator, or you would need to dereference it with the ‘*’ operator.

INTP
"Program testing can be used to show the presence of bugs, but never to show their absence."Edsger Dijkstra

Re: Base Class Reference

toxcct14-Jun-06 1:32

toxcct

14-Jun-06 1:32

John R. Shaw wrote:
If a reference was a constant pointer then you would need to use the ‘->’ operator instead of the ‘.’ Operator, or you would need to dereference it with the ‘*’ operator.

...and it would be not possible to alter the object referenced...

TOXCCT >>> GEII power

[VisualCalc 3.0 updated ][Flags Beginner's Guide new! ]

Re: Base Class Reference

John R. Shaw14-Jun-06 1:54

John R. Shaw

14-Jun-06 1:54

True! But what would also be true is that you could set the reference equal to anouther object if you wanted. Which C++ will not allow you to do whether it is a constant reference or not.

INTP
"Program testing can be used to show the presence of bugs, but never to show their absence."Edsger Dijkstra

Re: Base Class Reference

John R. Shaw14-Jun-06 0:55

John R. Shaw

14-Jun-06 0:55

I have been programming for a long time and have never tried doing what you are showing. Does the compiler actually let you set a reference to a base class object to a derived class object. I would understand if you where setting a pointer to a base class object to the address of a derived class object, but regardless of what you have heard a pointer and a reference are not exactly the same thing (although they are related).

You can set a pointer to a base class the address of an object derive from that same class. That is part of the power of C++; if you have a base class for shapes you want to draw and the base class has a virtual function for drawing shapes, then you can build an array of pointers to base class objects and then call the draw function for each of those objects. It is the derived class that does the actual drawing via the virtual function.

INTP
"Program testing can be used to show the presence of bugs, but never to show their absence."Edsger Dijkstra

Re: Base Class Reference

Sarath C14-Jun-06 1:19

Sarath C

14-Jun-06 1:19

I know a base pointer can be used to call derived class function (the object which points to). As you I haven't tried it yet...It came as the part of design suggestion. I just wondered and tried with the sample. Smile | :)

Sa^Rath.

"Don't Do Different things... Do Things Differently..."

Understanding State Pattern in C++

Re: Base Class Reference

John R. Shaw14-Jun-06 1:39

John R. Shaw

14-Jun-06 1:39

But you said you had not tried it! Did it actually work? It would not surprize me if it did; I have just never thought it would. A reference is basically a dereference pointer; that is the compiler dereferences it for you.

INTP
"Program testing can be used to show the presence of bugs, but never to show their absence."Edsger Dijkstra

Re: Base Class Reference [modified]

_AnsHUMAN_ 14-Jun-06 1:07

_AnsHUMAN_

14-Jun-06 1:07

Just to make things clear:
There are 3 classes A,B and C
B and C are derived from A : A has a virtual fn Display() and an int variable is declared in each class i,j and k respectively.
** And yes each class has a constructor where i assign a value to the variable's i,j,k respectively.
When we use pointers we can call :

    B b;
C c;
A* a=&c;
a->display(); // Prints value of K
a=&b;
a->display(); // Prints value of J

But when we use references :

B b;
C c;
A& a=c;
a.display(); // Value of K is printed
a=b;
a.display(); // Again the value of K is printed

Somethings seem HARD to do, until we know how to do them.
Wink | ;-)

_AnShUmAn_

-- modified at 7:09 Wednesday 14th June, 2006

Re: Base Class Reference

Sarath C14-Jun-06 1:22

Sarath C

14-Jun-06 1:22

Its known that a reference can't be re initalized. But i just wanted to know what is happening when compiling the code A& a=c;

Sa^Rath.

"Don't Do Different things... Do Things Differently..."

Understanding State Pattern in C++

Re: Base Class Reference

Laxman Auti14-Jun-06 2:28

Laxman Auti

14-Jun-06 2:28

wrote:
Its known that a reference can't be re initalized. But i just wanted to know what is happening when compiling the code A& a=c;

A reference holds the address of an object, but behaves syntactically like an object
Now come to point what happening in A& a=c; code

'a' holds the address of the 'c' and no need of dereferencing of 'a'

Knock out 't' from can't,
You can if you think you can
Cool | :cool:

Re: Base Class Reference

Naveen14-Jun-06 1:21

Naveen

14-Jun-06 1:21

check this
http://www.codeproject.com/useritems/References_in_c__.asp[^]

nave

Reduce the size of ssleay.lib and libeay.lib file [modified]

sunit514-Jun-06 0:25

sunit5

14-Jun-06 0:25

Can anybody tell me how to reduce the size OpenSSL LIB ie ssleay32.lib and libeay.lib.

Thanx in advance.

never say die

-- modified at 6:25 Wednesday 14th June, 2006

Re: Reduce the size of ssleay.lib and libeay.lib file

Christian Graus14-Jun-06 1:07

Christian Graus

14-Jun-06 1:07

Do you have the source code ? You can remove stuff you don't need, optimise the build for size ( not speed ), etc.

Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog

char* to CString [modified]

shuchigo_jane14-Jun-06 0:24

shuchigo_jane

14-Jun-06 0:24

Can i do the foll conversion...

char * str1="abc";
CString str2=;
str2=str1;

-- modified at 6:24 Wednesday 14th June, 2006

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