Question

A constructor that takes a single parameter of a type different from the class type is a ______________ constructor.

Short answer

A constructor that takes a single parameter of a type different from the class type is called a "conversion constructor."

Step-by-step solution

Identify the type of constructor

First, think about the different types of constructors we have in object-oriented programming. The constructor in question takes a single parameter with a type different from the class type, which means it is used to create an object from another object or data type. This type of constructor is known as a "conversion constructor."

Provide the answer

A constructor that takes a single parameter of a type different from the class type is called a "conversion constructor."

Key concepts

Understanding Object-Oriented Programming

Object-oriented programming (OOP) is a paradigm centered around objects rather than actions, and data rather than logic. In OOP, the concept of 'objects' is used to mirror elements in the real world, and these objects hold both data and methods. The data is represented by attributes, and the methods are functions that can modify these attributes.

OOP is built on several key principles: encapsulation, which means restricting direct access to some of an object's components; inheritance, a way to form new classes using classes that have already been defined; polymorphism, the process of using a single interface to control access to a general class of actions; and abstraction, the process of handling complexity by hiding unnecessary details from the user.

The objects are created from blueprints known as 'classes', which define the state and behavior that the objects of the class all share. An object is an instance of a class. When programming in an object-oriented language such as C++, these concepts come to play a significant role in defining how problems are structured and solved.

Constructors in C++

In C++, a constructor is a special type of member function that initializes objects of its class. It is invoked automatically when an object is created. Constructors have the same name as the class and do not have a return type, not even void.

There are various types of constructors: default constructors, which do not take any arguments; parameterized constructors, which use given parameters to initialize an object; copy constructors, which create an object by copying variables from another object; and move constructors, which transfer resources from one object to another.

The usage of constructors greatly simplifies the process of object creation, ensuring that an object starts its life in a valid state, with its fields properly initialized. Understanding constructors is a fundamental aspect of working effectively with C++ and embracing its object-oriented nature.

Conversion Constructor Definition

A conversion constructor in C++ is a specific type of constructor that enables implicit or explicit conversion from one type to another. It is defined as a constructor that accepts a single parameter of a different type from the one being constructed, excluding the cases of the parameter being of the object's class type or a reference to that object's type.

For instance, if we have a class named 'Time' and another class 'Seconds', a conversion constructor will allow us to create a 'Time' object directly from a 'Seconds' object.

Here's an example of what a conversion constructor in C++ might look like:
class Time {public: Time(const Seconds& sec);};

However, it's important to be cautious as conversion constructors can sometimes lead to unintuitive behavior when implicit conversions occur where they are not expected. For this reason, they can be marked with the 'explicit' keyword to avoid unintended conversions.