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Any ideas why I keep getting this error?
http://codepad.org/jPQzMWvG
You declared a destructor in the header (line 36), but you haven't defined it in the source code. Add this to the source code, and you should be fine :
Entity::~Entity()
{
// do the cleanup here
}
Your class definition includes a destructor ~Entity but there's no implementation for it in the Entity.cpp file.
You've declared a destructor ~Entity() (and also ~Block()), but not implemented them anywhere. If the destructors are necessary, then implement them; otherwise, remove the declarations.
By the way, you should post the code in the question rather than an external website.
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I'm still learning about using COM objects.
I'm trying to figure out where the values of CLSID_FileOpenDialog and IID_IFileOpenDialog are defined: https://learn.microsoft.com/en-us/windows/win32/learnwin32/example--the-open-dialog-box
I couldn't find them in the included header files.
From one example I saw, I figured that I'd need .c and .h files with the interface and class GUIDs, but I couldn't find any reference of them for online.
They are declared as extern variables in ShObjIdl_core.h, which is included by ShObjIdl.h, which the example you linked to is including.
The actual values are defined in uuid.lib, which your project needs to link to, otherwise you will get linker errors when it can't resolve the variables.
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I know that we can directly assign same class objects in C++,but what actually happen behind the scene?
There's something called "default copy-constructor" and "default assignment-operator". Unless you overload these methods in the class, the default behavior is that all non-static members of the class are copied one-by-one from the source to the target class.
A little more: This includes pointers, btw. Which is why you generally should overload these operators and follow the rule of three if you have pointers as members.
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Hy, my question is simple..
I have this function.
CPythonMessenger::CPythonMessenger(): m_poMessengerHandler(NULL)
{
}
What scope have and why is there since constructor is empty and also is not used m_poMessengerHandler(NULL) i want to say the function is not used anywhere is constructor.
I guess you are examining (or maybe it is your code) THIS.
CPythonMessenger is the default constructor for the class CPythonMessenger as you can see in the relative header file HERE. After the : you can invoke a method (or another constructor) that must be run when creating an object of CPythonMessenger type. In particular, it creates an instance of m_poMessengerHandler that is then used in several place in the other class methods.
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Please provide a simple solution to restrict inheritance in C++.
Yes! As of C++11, there's a final specifier you can use to indicate that a class cannot be inherited from:
class DontInheritMe final {
// This class cannot be inherited from.
};
If you have experience in Java, the final keyword in C++ in this case works the same was as final classes in Java.
If u really dont want to inherit a class,then just make its member variables and member functions as private ,if other class tries to inherit it they cant have access to its funtions and variables anyways.
But using final is a better option
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I am a newbie programmer in C++, I already know that I can use extern keyword to access functions and global variables on the other files in my project but the problem that I faced to, is that how can I use structs, enums placed (available in other files of my project) in my current .cpp file?
T.I.A
You should declare them in a header file, then #include them when you need them. You can still define them in a cpp file.