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Base
classes are typically used to establish the common
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attributes
and behavior for an application and to all
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classes
derived from it. .
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A
derived class may then be used to refine and add to the
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base
class and represent specialized versions, with new or
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altered
data/operations.
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The
relationship between a derived class and its base
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class
is often called an "is a" relationship. This is
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because
a derived class "is a" base class.
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A
derived class is everything the base class is and more,
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because
it has been extended or specialized. A derived
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class
object can be used when a base class object is
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needed.
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