C / C++ / MFC

Rajkumar R15-Mar-08 10:07

15-Mar-08 10:07

I guess you need to learn the basics of build systems and the entities project and workspace. adding a project to workspace containing the main project and setting the dependency doesnot include the definition of functions or variables to the main project whose symbols are still considered unresolved at the linking stage of main project. If you are looking Main and Sub to be combined as single application you can make the sub as library project and link the sublibrary statically or dynamically yo the main project. Or add all the source files to the main project making it a single project. Or Main and sub as separate app and use IPC to interface each other.

In your case i think you just add all the source files to main project and build it.

bala_potty16-Mar-08 0:08

bala_potty

16-Mar-08 0:08

Thank you Raj, But when I tried add all the source files of SUB to main project and buid it the .rc file of SUB is not getting Compiled.
Is there anyway this can be resolved?
Infact both MAIN & SUB are MFC AppWizard build .EXE projects. Pl. let me Know how to Convert SUB into DLL. so that Main and Sub to be combined as single application. Your suggestion will be of great help to me.

bala_potty

Rajkumar R16-Mar-08 21:41

16-Mar-08 21:41

bala_potty wrote:
buid it the .rc file of SUB is not getting Compiled

Its better to work with multiple resource files and multiple resource symbol header Changing the Names of Symbol Header Files[^]

TN035: Using Multiple Resource Files and Header Files with Visual C++ [^]

bala_potty wrote:
let me Know how to Convert SUB into DLL

Search for articles in web and cp for "MFC DLLs" "Regular DLLs"
Regular DLLs Dynamically Linked to MFC[^]

Regular DLLs Statically Linked to MFC[^]

learn something, and ask doubts (expecting valid good questions).

std::find [By any chance my question is not clear?]

bala_potty6-Apr-08 2:18

bala_potty

6-Apr-08 2:18

Got it Thanks. Smile | :)

bala_potty

_808615-Mar-08 4:29

_8086

15-Mar-08 4:29

In the below example, I just push some pointers to objects of type myClass into the vector. Previously, When I pushed just the objects as such, the find algo worked with the overloaded "==". But it's now pointers inside the vector. And I want the find algo still to find it, with integer as the passed argument for it. How can I do it?

class myClass
{
public:
	int x;
	int y;
	bool operator == (const int& n)
	{
		cout<<"\nCheck";
		cout<<"\n"<<n<<"\t"<<x;
		return(n==x);
			
	}
	
};

        std::vector<myClass*> vec_myClass;
	myClass* obj = new myClass();
	obj->x=1;
	obj->y=1;
	vec_myClass.push_back(obj);
	myClass* obj2= new myClass();
	obj2->x=2;
	obj2->y=2;
	vec_myClass.push_back(obj2);
	int n=2;
	vector<myClass*>::iterator itr_vec = vec_myClass.begin(); 
	itr_vec	=std::find(vec_myClass.begin(),vec_myClass.end(),n);//Compilation error here.

<br />
 itr_vec =std::find(vec_myClass.begin(),vec_myClass.end(),n); <br />

Here it's not taking "n" , and I can also guess why isn't taking. It actually expects an overload of == where we pass a pointer to the object itself. Is there anyway I can do it? Just by passing int?

----------------------------
286? WOWW! Blush | :O

modified on Saturday, March 15, 2008 1:37 PM

Re: std::find [By any chance my question is not clear?]

Rajkumar R15-Mar-08 9:39

Re: std::find [By any chance my question is not clear?]

15-Mar-08 9:39

_8086 wrote:
It actually expects an overload of == where we pass a pointer to the object itself. Is there anyway I can do it? Just by passing int?

Atleast one formal parameter of operators must be of non pointer class type, otherwise you can simply add a global operator == for type "myClass *" and int. But you can achieve it very easily with a another class which exposes the overloaded operator.

say,

class CSearchKey
{
public:
	int m_iVal;
	CSearchKey(int iVal)
		:m_iVal (iVal)
	{
	};
};

inline bool operator == (const myClass *pObj, const CSearchKey &rKey)
{		
	return(*pObj==rKey.m_iVal);	// calls myclass==int			
}

And in your original code you only want to change as follows.

itr_vec =std::find(vec_myClass.begin(),vec_myClass.end(),CSearchKey(n));

hope this solves.

_808615-Mar-08 17:21

_8086

15-Mar-08 17:21

Hello Rajkumar, thanks for your effort. I get these following errors. How did you manage to compile? I'm using VC8.0

error C2804: binary 'operator ==' has too many parameters
error C2333: 'myClass::operator ==' : error in function declaration; skipping function body

The whole program:

class CSearchKey
{
public:
	int m_iVal;
	CSearchKey(int iVal)
		:m_iVal (iVal)
	{
	};
};

class myClass
{
public:
	int x;
	int y;
	/*
	bool operator == (const int& n)
	{
		cout<<"\nCheck";
		cout<<"\n"<<n<<"\t"<<x;
		return(n==x);
			
	}
	*/
	 inline bool operator == (const myClass *pObj, const CSearchKey &rKey)
	{		
	return(*pObj==rKey.m_iVal);	// calls myclass==int			
	}	
};

int _tmain(int argc, _TCHAR* argv[])
{
	

	std::vector<myClass*> vec_myClass;
	myClass* obj = new myClass();
		obj->x=1;
	    obj->y=1;
	vec_myClass.push_back(obj);
	myClass* obj2= new myClass();
	obj2->x=2;
	obj2->y=2;
	vec_myClass.push_back(obj2);
	int n=2;
	vector<myClass*>::iterator itr_vec = vec_myClass.begin(); 
	itr_vec	=std::find(vec_myClass.begin(),vec_myClass.end(),CSearchKey(n));
 
	if(itr_vec!=vec_myClass.end())
	cout<<"\n\nResult:"<<(*itr_vec)->x<<"\n\n";

	return 0;
}

----------------------------
286? WOWW! Blush | :O

Re: std::find [By any chance my question is not clear?]

Rajkumar R15-Mar-08 18:00

Re: std::find [By any chance my question is not clear?]

15-Mar-08 18:00

the newly suggested operator is to be in global scope not in the class myclass, and you commented the already existing operator but that is used in the global == operator. Don't you see == operator takes multiple parameter its not a class member.

keep your code unchanged, don't comment the == operator in myclass. then the move the inline == operator to global, just below the CSearchKey class, use it in a header so that if you are using it in multiple cpp file this becomes inline and no additional code is generated for this. only thing you have to modify in your original code is whenever you search for int n search with CSearchKey(n). Try and let me know.

_808615-Mar-08 19:07

_8086

15-Mar-08 19:07

Great that's works! Thanks a lot. But why is not taking int as a parameter for == ? What harms it?
For example,

<br />
inline bool operator == (const myClass *pObj,const int& n)<br />
{		<br />
	return(pObj->x==n);<br />
}<br />
itr_vec	=std::find(vec_myClass.begin(),vec_myClass.end(),n);<br />

instead of,

<br />
inline bool operator == (const myClass *pObj,const CSearchKey &rKey)<br />
{		<br />
	return(return(pObj->x ==rKey.m_iVal););<br />
}<br />
itr_vec	=std::find(vec_myClass.begin(),vec_myClass.end(),CSearchKey(n));<br />

Why does it require a paramter of class type??

operator ==' must have at least one formal parameter of class type

I dont understand this requirement.

----------------------------
286? WOWW! Blush | :O

Re: std::find [By any chance my question is not clear?]

Rajkumar R16-Mar-08 22:58

16-Mar-08 22:58

if both parameters are pointers or primitive types it takes pure comparison of values. (int and void *).

_8086 wrote:
But why is not taking int as a parameter for == ?

you can have wrapper for "myClass *", ptrMyClass as we did for int, CSearchKey.
then inline bool operator == (const myClass *pObj,const int& n) can be used as
inline bool operator == (const ptrMyClass &ptrObj,const int& n) but then you have to store in vector as vector<ptrmyclass>.

Compilation Firewalls

George_George15-Mar-08 2:57

Re: Compilation Firewalls

15-Mar-08 2:57

Hello everyone,

Any ideas why Pimpl idiom is called "Compilation Firewalls"? Smile | :)

http://www.gotw.ca/gotw/024.htm

I have thought for a while, and I think client code does not need to compile in Pimpl idiom, so like a firewall to block compile, it is called "Compilation Firewalls".

Any ideas why it is named "Compilation Firewalls"?

thanks in advance,
George

Maximilien15-Mar-08 3:34

Maximilien

15-Mar-08 3:34

Probably because Herb Sutter (the author of GoTW) liked it ?

pimpl, when well executed, will prevent (thus a "firewall" or insulating) a lot of dependent re-compilation when the private implementation
of a class changes.

dependent of a class should never, in the best case, know the private implementation of a class; I've even seen some design that put all private methods as free functions in the code.

Maximilien Lincourt
Your Head A Splode - Strong Bad

Re: Compilation Firewalls

George_George15-Mar-08 3:55

Windows Services: User account management

15-Mar-08 3:55

Thanks Maximilien,

Question answered.

regards,
George

tony_Udz15-Mar-08 2:47

tony_Udz

15-Mar-08 2:47

Hello,

I am naive to Windows Services.
I have few queries regarding Windows Services which are as follows: -

How to manage User account?
For example there are several users present on a single machine and how to restrict users group from accessing the Windows Service?

Can do it using CoInitializeSecutriy(), if yes then How?

Thanks in Advance.

why private virtual function?

George_George15-Mar-08 2:11

15-Mar-08 2:11

Hello everyone,

Why do we need to fine a virtual function as private? As special functions we can achieve and any special limitaitons?

thanks in advance,
George

Vasudevan Deepak Kumar15-Mar-08 3:03

Vasudevan Deepak Kumar

15-Mar-08 3:03

Check this out http://www.dbforums.com/showthread.php?t=1576535[^]

Vasudevan Deepak Kumar
Personal Homepage
Tech Gossips

A pessimist sees only the dark side of the clouds, and mopes; a philosopher sees both sides, and shrugs; an optimist doesn't see the clouds at all - he's walking on them. --Leonard Louis Levinson

George_George16-Mar-08 0:01

16-Mar-08 0:01

Thanks Vasudevan,

Great link! Especially this one, http://www.gotw.ca/publications/mill18.htm[^]

I have a further question, it is always mentioned "preconditions and postconditions", like in the above link, what means "preconditions and postconditions" in the article?

--------------------
First, note that the base class is now in complete control of its interface and policy, and can enforce interface preconditions and postconditions, insert instrumentation, and do any similar work all in a single convenient reusable place - the nonvirtual interface function. This promotes good class design because it lets the base class enforce the substitutability compliance of derived classes in accord with the Liskov Substitution Principle[3], to whatever extent enforcement makes sense. If efficiency is an issue, the base class can elect to check certain kinds of pre- and postconditions only in a debug mode, for example via a non-debug "release" build that completely removes the checking code from the executable image, or via a configurable debug mode that suppresses selected checking code at runtime.
--------------------

regards,
George

Maximilien15-Mar-08 3:36

Maximilien

15-Mar-08 3:36

we don't need them, so don't use them.

Maximilien Lincourt
Your Head A Splode - Strong Bad

George_George15-Mar-08 3:54