Characteristics of Constructors

Constructors

• Objects need to initialize the variables. Such initialized variables can then be used for processing. If the variables are not been initialized then they hold some garbage value. And if such variables are taken for operation then unexpected results may occur. In order to avoid that the class can include a special function called constructor. The constructor can automatically be called whenever a new object of this class is created. The constructor will have the same name as the class name. It should not have any return type.

• In C++ there are various ways of using constructors. We will understand with the help of programming examples.

Characteristics of Constructors

• Following are some rules that must be followed while making use of constructors ‒

1. Name of the constructor must be same as the name of the class for which it is being used.

2. The constructor must be declared in the public mode.

3. The constructor gets invoked automatically when an object gets created.

4. The constructor should not have any return type. Even a void type should not be written for the constructor.

5. The constructor can not be used as a member of union or structure.

6. The constructors can have default arguments.

7. The constructors can not be inherited. But the derive class can invoke the constructor of base class.

8. Constructors can make use of new or delete operators for allocating or releasing the memory.

9. Constructors can not be virtual.

10. Multiple constructors can be used by the same class.

 11. When we declare the constructor explicitly then we must declare the object of that class.

Types of Constructors

• Various s types of constructors used in C++ are ‒

1. Default constructor

2. Parameterized constructor

3. Default argument constructor

4. Copy constructor.

Let us discuss them in detail.