Class Inheritance, Template

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Class Inheritance, Template STL

• COMP103 Lab 12

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Everything Could be A Class Object
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Are Objects of Different Classes Completely
Separated?

• Usually NO!
• Different classes are somewhat related
• E.g. Raymond has a bag
• E.g. Raymond is a boy

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Has a Is aRelationship

• Has a
• A class has some types as data members
• E.g. alphabetSet has an array
• Is a
• A class is also another class
• A derived class is inherited from another base
  class
• A derived class has all the features of a base
  class

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Inheritance

• Syntax

// class definition class derivedClass public
baseClass public func()
... private int member1 //
constructor initializing base class and data
members derivedClassderivedClass()
baseClass(...), member1(2)
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Inheritance

• Data members and member functions of base class
  are brought to derived class
• But visibility of base classs members to derived
  class is controlled by their access modifiers at
  base class
• public/protected at base class gt visible to
  derived class
• private at base class gt invisible to derived
  class
• But not all functions are brought to derived
  class (which of them?)

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Features of Inheritance

• Common components are grouped and implemented as
  a general base class
• More specific classes derive from base class
  which contain
• Shared features from base class
• Some specific features
• Reuse of code using a base class

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Class Template

• A class with unspecified type
• Provide generic data structure and functions on
  various data types

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Writing Class Template

• Put class definition and function member
  definitions in a single .h file
• Syntax

templateltclass Tgt // class definition class A
public func(T para)
... templateltclass Tgt // function member
definition AltTgtfunc(T para) ...
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Using Class Template

• Declaring a variable
• Altintgt variable1
• Altintgt variable2(4)
• Using member function
• variable1.func(2)

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Standard Template Library (STL)

• A collection of common containers, algorithms and
  iterators
• Allow users reuse the common items without
  writing the same codes repeatedly
• Reference of STL
• E.g. http//www.sgi.com/tech/stl/

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Common Containers

• Containers are data structures for storing data
  with various insertion/deletion/searching
  performance
• Containers in STL are designed with similar
  function prototypes
• Simplified programming
• Ease for performance tuning
• E.g. linked lists, vector, etc

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Using STL

• Include the corresponding library
• Add the statement
• using namespace std