Question

What is a default constructor?

Short answer

Answer: A default constructor is a special constructor that the compiler automatically provides when no other constructors are explicitly defined within a class. Its main purpose is to create objects with a default state, meaning their attributes have default values. This process initializes the object and ensures smooth functioning in the instantiation phase.

Step-by-step solution

Define a constructor

In object-oriented programming, a constructor is a special method within a class responsible for initializing newly created objects of that class. It typically has the same name as the class and runs automatically when an object is created. Constructors can take parameters to set initial values for the object attributes.

Explain the purpose of a default constructor

A default constructor is a constructor that is automatically provided by the compiler when no other constructors are explicitly defined within the class. It takes no arguments and contains no code within its body. Its primary purpose is to create objects with a default state, i.e., with default values for their attributes.

Provide an example of a default constructor

Let's consider a simple class called `Person`. If no constructor is defined for the `Person` class, the compiler will automatically create a default constructor for it. ``` class Person { public: std::string name; unsigned int age; }; ``` In this case, the default constructor is implicitly created by the compiler. The following code demonstrates how to create a new object of the `Person` class using the default constructor: ``` int main() { Person person1; // Default constructor is automatically called here return 0; } ``` When an object of the `Person` class is created, the default constructor initializes the object with default values for its attributes, which are typically empty or zero depending on the data type.