Re: Inheritance issue - C / C++ / MFC Discussion Boards

Inheritance issue [modified]

big_denny_20029-May-06 3:22

big_denny_200

29-May-06 3:22

hello

I've found my silly mistake

please help me find error in my code :

// *************
class Base
{
	public : 

 		virtual ~Base() {};

		// Retrieve value of X
		virtual void getX() const
		{
			cout<<endl<<"Inside Base : "<<m_X<<endl;
		};

protected : 
		int	m_X;
};

// *************
class Derived1 : public Base
{
public : 
	
	// Constructor
	Derived1()
		:Base()
	{
		m_X = 100;
	};

	// Retrieve value of X
	virtual void getX() const
	{
		cout<<endl<<"Inside Derived1 : "<<m_X<<endl;
	};
};
 
// *************
int _tmain(int argc, _TCHAR* argv[])
{
	try
	{
	throw Derived1(); 
	}

	catch (Base *pError) // should be &pError here
	{
		pError->getX(); // and .getX() here 
	}

	return 0;
}

sorry for stupid question

I am pretty tired, need a good sleep Smile | :)

-- modified at 9:42 Monday 29th May, 2006

Re: Inheritance issue [modified]

toxcct29-May-06 3:26

toxcct

29-May-06 3:26

big_denny_200 wrote:
virtual void getX() const {
cout<<endl<<"inside base="" :="" "<<m_x<<endl;
}<b="">;

~~don't close your functions definitions with semicolons (';').~~
at last, just curious... don't you understand what the compiler says when complaining ?! Poke tongue | ;-P

i have no compiler to test here, so, sorry.

TOXCCT >>> GEII power

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

-- modified at 9:45 Monday 29th May, 2006

Re: Inheritance issue [modified]

big_denny_20029-May-06 3:30

big_denny_200

29-May-06 3:30

why not use semicolons ?

thanks
-- modified at 9:34 Monday 29th May, 2006

Re: Inheritance issue [modified]

toxcct29-May-06 3:36

toxcct

29-May-06 3:36

big_denny_200 wrote:
why not use semicolons ?

and you didn't answer my questions more.

* What are the compiler errors ?

TOXCCT >>> GEII power

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

-- modified at 9:45 Monday 29th May, 2006

Re: Inheritance issue

Cedric Moonen29-May-06 3:43

Cedric Moonen

29-May-06 3:43

toxcct wrote:
because the C++ doesn't want them here

In fact, this won't change anything. You can let them there. They will simply be ignored.

Cédric Moonen
Software developer

Charting control

Re: Inheritance issue

Sarath C29-May-06 3:46

Sarath C

29-May-06 3:46

Cedric have u seen my post? I think that is the reason for his assertion?

Sa^Rath

"D on't blindly follow rules you read somewhere without verifying that it makes sense for your situation!"

Re: Inheritance issue

Sarath C29-May-06 3:45

Sarath C

29-May-06 3:45

a function ending with ";" is simply compiling with visual studio .net and visual studio 6 C++ compiler.

Sa^Rath

"D on't blindly follow rules you read somewhere without verifying that it makes sense for your situation!"

Re: Inheritance issue

Sarath C29-May-06 3:38

Sarath C

29-May-06 3:38

it is not the problem with a ";"

problem is with ur try catch block;

big_denny_200 wrote:
catch (Base *pError)

u r catching a pointer to the throwing object but inside the
try block u r doing

big_denny_200 wrote:
throw Derived1(); // when I add this line I get assert

so inside the throw block do as follows

Derived1 d; // when I add this line I get assert
throw &d;

or

throw &Derived1(); // when I add this line I get assert

u can also resolve if u change the catch block to pass by value instead pass by reference

Sa^Rath

"D on't blindly follow rules you read somewhere without verifying that it makes sense for your situation!"

Re: Inheritance issue

Stephen Hewitt29-May-06 14:32

Stephen Hewitt

29-May-06 14:32

SaRath C wrote:
Derived1 d; // when I add this line I get assert
throw &d;

Never do this as it’s seriously flawed. The object d is on the stack but the stack is unwound when an exception is caught. The upshot is that when you catch an exception with such code the exception handler gets a pointer to an object which no longer exists. It's the same situation as returning a reference or pointer to a local variable from a function.

Steve

Re: Inheritance issue [modified]

Stephen Hewitt29-May-06 14:37

Stephen Hewitt

29-May-06 14:37

You're throwing a Derived1 but catching a Base*. If you want to catch a Base* you need code like this:

try
{
    throw new Derived1(); 
}
catch (Base *pError)
{
    pError->getX();
    delete pError;
}

A better was is not to throw a pointer. Use code like this:

try
{
    throw Derived1(); 
}
catch (const Base &e)
{
    e.getX();
}

Steve

Context Menu - Adding an Item in the Windows explorer context menu

Tamal Saha29-May-06 3:11

Tamal Saha

29-May-06 3:11

Probably you have seen "winrar" to add "Add to archive" type menuitem to default right-click pop-up menu. I want to add this feature to my file conversion software. After some searching on the internet, I think I have to modify the Windows Explorer context menu. I don't know how to do it. Does anyone know how to do it?

Tamal Saha,
Student,
Bangladesh University of Engineering and Technology.

Re: Context Menu - Adding an Item in the Windows explorer context menu

toxcct29-May-06 3:16

toxcct

29-May-06 3:16

look here[^]... the series of Mike Dunn's Complete Idiot Guide to Shell Extensions is very interresting.

TOXCCT >>> GEII power

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

Re: Context Menu - Adding an Item in the Windows explorer context menu

Owner drawn29-May-06 17:37

Owner drawn

29-May-06 17:37

toxcct wrote:
Complete Idiot Guide

Owner drawn
Jesus Loves

Re: Context Menu - Adding an Item in the Windows explorer context menu

toxcct29-May-06 21:22

toxcct

29-May-06 21:22

i didn't name it myself Roll eyes | :rolleyes:

ps: nice to see you back dear... where were you for all these days ?

TOXCCT >>> GEII power

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

Re: Context Menu - Adding an Item in the Windows explorer context menu

Owner drawn30-May-06 21:12

Owner drawn

30-May-06 21:12

toxcct wrote:
i didn't name it myself

Thinking about the guys who read it. Roll eyes | :rolleyes:

toxcct wrote:
ps: nice to see you back dear... where were you for all these days ?

Thanks. My ghost was always present here. Poke tongue | ;-P

Owner drawn
Jesus Loves

Re: Context Menu - Adding an Item in the Windows explorer context menu

toxcct30-May-06 21:39

toxcct

30-May-06 21:39

Owner drawn wrote:
Thinking about the guys who read it.

i did BTW

TOXCCT >>> GEII power

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

C++/CLI

Sarath C29-May-06 3:10

Sarath C

29-May-06 3:10

Is it really interesting to code with .net framework + C++.

I could not enter into the new world something resisting me to do that Frown | :(

what is ur opinion about new C++ versions and coding with .net?

Sa^Rath

Re: C++/CLI

toxcct29-May-06 3:13

toxcct

29-May-06 3:13

you'd better ask this in the C++/CLI forum or even in the lounge...

personnaly, i'm not interrested at all in coding for the .NET framework for the moment, in whatever language i could use...

TOXCCT >>> GEII power

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

Re: C++/CLI

Sarath C29-May-06 3:22

Sarath C

29-May-06 3:22

toxcct wrote:
personnaly, i'm not interrested at all in coding for the .NET framework for the moment, in whatever language i could use...

Thanks for ur reply

Sa^Rath

"D on't blindly follow rules you read somewhere without verifying that it makes sense for your situation!"

Re: C++/CLI

Sarath C29-May-06 3:30

Sarath C

29-May-06 3:30

toxcct wrote:
you'd better ask this in the C++/CLI forum or even in the lounge...

if i post this question in C++/ CLI they will kick me off from there Cry | :((

why should we take a risk? there are many supporters for that but here we can get mixed opinions that's y I posted here Smile | :)

Sa^Rath

"D on't blindly follow rules you read somewhere without verifying that it makes sense for your situation!"

Re: C++/CLI

toxcct29-May-06 3:33

toxcct

29-May-06 3:33

SaRath C wrote:
if i post this question in C++/ CLI they will kick me off from there

only stupid guys will...

SaRath C wrote:
why should we take a risk?

because i think most people on this forum don't know managed C++ ,and even if they do, it's not the topic of this board to talk about that kind of things.

and as i think this is not a programming question but more a general knowledge question, it worth it asking the lounge Wink | ;)

TOXCCT >>> GEII power

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

How to write the current status in some file when system shuts down with Electricity failure

zahid_ash29-May-06 1:53

zahid_ash

29-May-06 1:53

Hi,

Before closing my application I write down the status of current working in some file.
But when the application gets closed after sudden electricity failure, how can I write down the status in a file at that time.

any Idea? / link

Regards.

Re: How to write the current status in some file when system shuts down with Electricity failure

Nibu babu thomas29-May-06 2:06

Nibu babu thomas

29-May-06 2:06

zahid_ash wrote:
But when the application gets closed after sudden electricity failure,

AFAIK there are none. WM_QUERYENDSESSION and others do help only if you are using Shut Down.

Nibu thomas
A Developer

Programming tips[^] My site[^]

Re: How to write the current status in some file when system shuts down with Electricity failure

Eytukan29-May-06 2:07

Eytukan

29-May-06 2:07

How can you write when the system has shut down?? Confused | :confused:

and Btw is this you really ask?

<marquee scrollamount="1" scrolldelay="1" direction="up" height="10" step="1">--[V]--

[My Current Status]

Re: How to write the current status in some file when system shuts down with Electricity failure

zahid_ash29-May-06 2:23

zahid_ash

29-May-06 2:23

Mean to say that I want to write in a file( open a file and write status data in it)just before Operating system is shutting down with electricity failure

Regards.

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