VC++ - Visual C++ - Microsoft Visual C++ Interview Questions And Answers

When designing a class hierarchy, you may face a decision between inheritance (aka IsA ) vs. containment (aka HasA) relation. For instance, if you are designing a Radio class, and you already have the following classes implemented for you in some library: Dial, ElectricAppliance. It is quite obvious that your Radio should be derived from ElectricAppliance. However, it is not so obvious that Radio should also be derived from Dial . How to decide? You can check whether there is always a 1:1 relation between the two, e.g., do all radios have one and only one dial? You may realize that the answer is “no”: a radio can have no dial at all (a transmitter/receiver adjusted to a fixed frequency) or may have more than one (both an FM dial and AM dial). Hence, your Radio class should be designed to have Dial(s) instead of being derived from it. Note that the relation between Radio and ElectricAppliance is always 1:1 and corroborates the decision to derive Radio from ElectricAppliance

C++ defines a set of generic algorithms such as sort and find. However, the corresponding C algorithms, qsort and bsearch, are still useful in C++ programs for at least three reasons: • Legacy code. Familiarity with C algorithms is needed to maintain legacy C code. • Efficiency. You cannot apply STL algorithms to items that are not stored in an STL container. To apply these algorithms to a built-in array, you first have to copy it into a container--an operation that incurs runtime overhead. • Applicability to non-OO data types. STL algorithms rely on operators == and >. However, these operators are either meaningless or not defined when applied to plain structs or built-in arrays. C algorithms do not rely on these operators to work.

The term binding refers to the connection between a function call and the actual code executed as a result of the call. Early Binding: If which function is to be called is known at the compile-time it is known as static or early binding. Dynamic Binding: If which function is to be called is decided at run time it is called as late or dynamic binding. Dynamic binding is so called because the actual function called at run-time depends on the contents of the pointer. For example, call to virtual functions, call to functions to be linked from dlls use late binding.

A template function cannot be distributed in the obj form. This is because, fuction with which parameters the template function is going to be called is decided at the run time only. Therefore an obj form of a template function cannot be made by merely compiling it.

No. The virtual function mechanism is used on the specific object that determines which virtual function to call. Since the static functions are not any way related to objects, they cannot be declared as virtual.

Yes. The ANSI committee added the bool intrinsic type and its true and false value keywords. Other apparent new types (string, complex, and so on) are implemented as classes in the Standard C++ Library rather than as intrinsic types

Multiple providers of libraries might use common global identifiers causing a name collision when an application tries to link with two or more such libraries. The namespace feature surrounds a library's external declarations with a unique namespace that eliminates the potential for those collisions.