Inheritance is a process by which one class acquires the members of an existing class. It describes a hierarchical relationship between classes. For example, a lion is a kind of animal. Now talking in terms of object-oriented programming, it can be said that Lion is a subclass of Animal, and Animal is a super class of Lion.
By use of inheritance, a class inherits the general attributes and behaviors from its super class, and defines only those members that make it unique. Inheritance exposes, extends, or alters the attributes and behaviors of the super class. A subclass can extend but cannot narrow its super class.
Following are the different forms of inheritance:
- Single inheritance
- Multilevel inheritance
- Hierarchical inheritance
- Multiple inheritance
In single inheritance, a class inherits implementation from only one super class. For example, if class B inherits from class A, class B will acquire all the members declared in class A.
In multilevel inheritance, a class inherits from a derived class (or subclass). For example, if class C inherits from class B, and class B inherits from class A, class C will acquire all the members declared in class B as well as all the members declared in class A.
In hierarchical inheritance, many sub classes inherit from a single super class. For example, if classes B, C, and D inherit from class A, classes B, C, and D will acquire all the members declared in class A.
In multiple inheritance, a class inherits from several super classes. For example, if class C inherits from both class A and class B, class C will acquire all the members declared in class A as well as all the members declared in class B. Multiple inheritance is not directly implemented by classes in Visual Studio .NET. However, this concept can be implemented using interfaces.
Reference: Visual Studio .NET Combined Collection, Contents: "Inheritance", "Inheritance Basics"
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