C++ Programming - Constructors and Destructors - Discussion

A class without any public constructor is not totally pointless, if it is a base class, and it has a protected constructor. Its' child class may be instantiated.

A class without any public or protected constructor is totally pointless. Neither this class nor its' child class is instatiatable, because the constructor of the child class must call the constructor of the base class, which is inaccessible from the child class if that constructor is private.

Compiler does not always provide zero value constructor. It does provide one such constructor when no other constructors are defined.

The option B will be correct as the compiler will not provide default constructor when user defined any constructor.

Compiler always provide parameter-less constructor, so option B is correct. But we can declare constructor as private so that we can create object of class outside member function for ex:constructor and copy constructor in singleton class is private.

How can constructor can't be private? If we consider design patterns, for singleton pattern implementation, constructor should be private.

Option C is correct.

1) Compiler doesn't ALWAYS provide a zero-argument constructor. It provides a zero-arg constructor only when the user hasn't defined any constructor explicitly.

2) Constructor need not be public always. If it private/protected we can create another public member function which can call the private/protected constructor.

The keyword "ALWAYS" changes the answer here.

When we want to execute the particular part of the program we can declare constructor as private or protected.

It can be any of them.

But compiler can automatically provide the default constructor.

How this answer is possible, as a constructor is always defined in public section of a class ?