Mastering C++: A Comprehensive Quiz Based on 'Thinking in C++'

What C++ feature allows a constructor to be called without any arguments, provided by the compiler if necessary?

1. Default constructor

2. Implicit constructor

3. Copy constructor

4. Parameterized constructor

The correct answer is: Default constructor

A default constructor is a special type of constructor that is automatically generated by the compiler if no other constructor is defined for a class. This constructor takes no arguments and initializes the object's data members with default values. This is why A is the correct answer. Option B, implicit constructor, is not a commonly used term in C++ and can be confusing. It is not a specific feature of the language. Option C, copy constructor, is used to create an object by copying the values of another object of the same class. It takes a reference to an object as an argument. While this constructor can also be called with no arguments, it is not a default constructor and serves a different purpose. Option D, parameterized constructor, is a constructor that takes parameters/arguments to initialize an object's data members. This is different from the default constructor, which takes no arguments.