C / C++ / MFC

How to protect a member function

2-Nov-14 5:49

ForNow wrote:
what role do the preprocessor flags play in the build

No idea, but as I said earlier, you should look at the makefile to see whether this value has been propagated correctly.

Drugodrf31-Oct-14 4:35

Drugodrf

31-Oct-14 4:35

Hi to all,
i write a class (A) that works with an object from another class (B); class B needs to call a method from class A, but i would like this function from class A it's not visible when i use class A for my projects.
Example: i write a numeric edit that use spin button; i write a spin button class derived from CSpinButtonCtrl and an edit class derived from a CEdit; edit have a function MyFunction() called from spin button class.
So, when i use numeric edit in my projects, i would like MyFunction() (and also all class spin button) is not visible (protected).
What is the correct way to do that, if it's possible ?

Thanks

Jochen Arndt31-Oct-14 5:18

Jochen Arndt

31-Oct-14 5:18

It seems that you are looking for friend[^].

For your example you can make your CEdit derived class a friend class of the spin control class:

C++

class CMyEdit : CEdit {
 friend class CMySpinControl;
protected:
 // This can be called from CMySpinControl.
 void MyFunction();
};

image processing toolkits | batch image processing

C^hris L^osinger31-Oct-14 5:18

C^hris L^osinger

31-Oct-14 5:18

make MyFunction private, and make A a friend of B.

friend classes
[^]

Drugodrf3-Nov-14 2:31

Drugodrf

3-Nov-14 2:31

As i can, i try.

Thanks to all

Albert Holguin3-Nov-14 11:39

Albert Holguin

3-Nov-14 11:39

An alternative to using "friend" classes would be to use messages and message handlers. In MS Windows, messages are what windows already use to communicate with one another. You can easily add new messages and handlers.

Aescleal4-Nov-14 2:29

Aescleal

4-Nov-14 2:29

(Bit late to the party... still think this is worth saying and it might help you in future)

If you ever find yourself wanting to use a class but there's aspects of it's interface that you don't want to work with then don't try and modify the class you want to use - that way lies madness and hackiness of the first degree. If the class with the relatively fat interface really needs a big interface somewhere else you don't want to break that. So what can you do about it? Wheel out the software engineer's swiss army knife - another level of indirection!

So if you've got a class:

C++

class fat_and_dangerous
{
	public:
		void safe();
		void dangerous();
};

and don't want clients to use dangerous() implement another class using it:

C++

class skinny_and_safe
{
	public:
		skinny_and_safe() : fat_( new fat_and_dangerous ) {}

		void safe() { fat_->safe(); }

	private:
		std::unique_ptr<fat_and_dangerous> fat_;
}

and in most of your client code only use skinny_and_safe.

Just out of interest... don't actually implement skinny_and_safe inline. It leaks too many implementation details to the client. Don't worry about performance - most compilers (actually linkers working with compilers) these days will elide the indirect call - until a profiler tells you that it's slow.

Drugodrf4-Nov-14 7:41

Drugodrf

4-Nov-14 7:41

Thanks very much to all: it's works and it's what i need.

For Albert Holguin and Aescleal: i think with "friends" it's more simple; thanks likewise.

I can't figure out why my program is not running

Aescleal4-Nov-14 21:27

Aescleal

4-Nov-14 21:27

Friends will work but you should always be aware of the coupling that introduces into your design.

Member 1119464630-Oct-14 18:47

Member 11194646

30-Oct-14 18:47

/* William Strickland
Project 3
Is Leap Year Portion

*/

#include <stdio.h>
#include <stdlib.h>
#include "..\..\stdbool.h"

bool isLeapYear(int *year);

int main(int argc, char *argv[])
{
int year = atoi(argv[4]);

printf("Name: William Strickland \n");
printf("Is Leap Year \n");

if (isLeapYear(&year))
{
printf("%d is a leap year", year);
}
else
{
printf("%d is not a leap year", year);
}

return 0;
}

bool isLeapYear(int *year)
{

if (*year % 4 == 0 && *year % 100 != 0)
{
return 1;
}

else if (*year % 100 == 0 && *year % 400 == 0)
{
return 1;
}

else
{
return 0;
}
}

Re: I can't figure out why my program is not running

enhzflep30-Oct-14 21:12

enhzflep

30-Oct-14 21:12

0. Please edit your question and wrap your code in the appropriate tags.
1. "Not running" isn't very descriptive. Are you failing to hit the enter key after typing the name of the program ina console window, are you only building the program but not running it from an IDE, or perhaps, you're running the program and it produces unexpected output..
2. The program runs just fine.
3. This is the output I get when running from the console. (I assume you understand what argv[4] refers to. Hint: it's not a 4 character long input. argv[0] would hold ~~"001-deleteMePlease"~~ "001-deleteMePlease.exe")

D:\code\001-deleteMePlease\bin\Release>001-deleteMePlease.exe 1 2 3 2000
Name: William Strickland
Is Leap Year
2000 is a leap year

"When I was 5 years old, my mother always told me that happiness was the key to life. When I went to school, they asked me what I wanted to be when I grew up. I wrote down 'happy'. They told me I didn't understand the assignment, and I told them they didn't understand life." - John Lennon

Resources for OOP practice for C++

Member 1119427030-Oct-14 14:12

Member 11194270

30-Oct-14 14:12

Hi there,

I have learned the principles of OOP and implementations in both java and C++ either on my own or in my school courses but we only grazed it. At this point, I feel very uncomfortable with OOP and I need a good resource that will provide me with a great deal of problems that require OOP to solve (or are best solved using object oriented approaches), and their respective answers with clean code and good practices. I have had very very little practice with OOP and want to practice as much as possible to get comfortable with it. I have been searching a lot but I can't seem to find a good resource.

Optimally, I would like it to begin with very trivial questions and progressively become more and more difficult.

Thank you.

Richard MacCutchan30-Oct-14 22:52

30-Oct-14 22:52

There are many books on the principles of Object Oriented Programming, and even more resources on the internet. You can try http://www.relisoft.com/index.htm[^], or http://docs.oracle.com/javase/tutorial/index.html[^] for examples of C++ and Java.

Message Closed

1-Nov-14 19:47

4india

1-Nov-14 19:47

Message Closed

Richard MacCutchan1-Nov-14 21:53

1-Nov-14 21:53

4india wrote:
I think you can refer this refer this site for knowledge buildup.

I think not; the first example I looked at is wrong.

OriginalGriff16-Nov-14 22:37

OriginalGriff

16-Nov-14 22:37

He's just spamming - why would he care if it works? Laugh | :laugh:

Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...

Richard MacCutchan16-Nov-14 22:46

16-Nov-14 22:46

Correct, more votes still needed.

Dump file creation

HungryCPPDev29-Oct-14 20:52

HungryCPPDev

29-Oct-14 20:52

Hi,

I want to generate a dump file automatically whenever the application crashed/hanged. Is there any option to do it or how to do it programatically as the developer don't know when that application crashes at client location.

Thanks in advance for your help.

den2k8830-Oct-14 0:37

den2k88

30-Oct-14 0:37

AFAIK Dump Files are managed by the OS - whichever it is - so you should look on the OS documentation. It is probable that you need to instruct the OS that you want a dump file and of which kind you desire (short, long, kernel...).

For example see if
http://msdn.microsoft.com/en-us/library/d5zhxt22.aspx[^]

is of any use for you.

HTH

HungryCPPDev30-Oct-14 20:37

HungryCPPDev

30-Oct-14 20:37

Hi,

Thanks for your reply.

bert_r30-Oct-14 5:16

bert_r

30-Oct-14 5:16

You can tell windows to create these dmp's for you (starting from Windows Server 2008 and Windows Vista SP1).
See MSDN for details: Collecting User-Mode Dumps[^]