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One of the beautiful features of ‘C++’ is its ability to support Operator Overloading. ‘C++’ Operator Overloading allows changing the behavior of operators when using them with ‘C++’ class objects. One of the best examples of Operator Overloading is the ‘+’ operator. Usually, the ‘+’ operator will add two integer operands and produce an integer […]
C/C++ allows passing the variable number of arguments to its functions through a variable argument list (va_list). C/C++ provides a series of macros/functions va_start, va_arg, va_end to allow passing the variable number of arguments to its functions. In this article, we will discuss how to implement this in C/C++. Step 1. We will prepare a […]
Inheritance allows reusing the functionality. Inheritance inherits base class members to its derived class. We can use base class members within the derived class without rewriting the base class code. C++ allows single inheritance as well as multiple inheritances. In single inheritance, the derived class is inherited from a single base class. In multiple inheritances, […]
In our previous article, we have created Type Library “Hello.tlb”. We were facing issues when we tried to add “HelloComponent.dll” as a reference to our Visual Basic test application. Hence we have created “Hello.tlb” Type Library. And we observed that even with “Hello.tlb” Type Library, Visual Basic test application (console based application) is showing error […]
We have created our COM component using C++ and we have tested our COM component in C++ based client application. We found that our COM component is working fine. Since our component is built on COM, it should work with client applications which developed using other languages like Visual Basic, Java, Visual C++ etc., This is one […]
Finally, we have successfully developed our COM component HelloComponent using C++. Let’s summarize how we developed our COM component in this article. Microsoft’s Component Object Model (COM) is a specification to allow to write of reusable components and enables them to communicate with each other. COM depends on interfaces to achieve its goals. One of […]
C++ Templates are used for writing generic programming. C++ allows defining the function templates and class templates. In C++, we use the template keyword to write generic programming. The syntax of the template declaration starts with template<class T> Where template is the keyword that indicates the particular function or class is a generic function or […]
CoCreateInstance depends on IClassFactory to create class instances. We have looked into IClassFactory‘s methods and we have implemented these methods in our previous article. Let’s include IClassFactory‘s implementation into our HelloComponent. We already have HelloComponent‘s declaration in the “HelloComponent.h” file and its implementation in the “HelloComponent.cpp” file. In the same way, we will add the IClassFactory […]
In our previous article, we have identified that CoCreateFunction is requesting an instance of IClassFactory. Why CoCreateInstance is requesting an instance of IClassFactory? One of the goals of the COM is to locate the objects easily without worrying about where they are located and where they are housed; whether they are housed in in-process, local, or remote. in-process means, the […]
As we discussed in our previous articles, COM’s CoCreateInstance function is used to create instances for COM classes. What is happening inside the CoCreateInstance function? When the client program calls CoCreateInstance to create an instance of COM class: It actually internally calls another function CoGetClassObject CoGetClassObject checks the registry entries for CLSID which was passed through […]