1 / 49

Understanding Abstract Data Types in C++ Programming

Learn about the concept of Abstract Data Types (ADTs) in programming, their implementation in C++, and practical examples using Rational ADT. Explore basic operations like addition, subtraction, multiplication, and division. Discover how to use default and copy constructors effectively.

michaelguy
Download Presentation

Understanding Abstract Data Types in C++ Programming

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. CHAPTER 7Implementing abstract data types抽象数据类型实现 Introduction A data abstraction is a representation of information and the operations to be performed on the information. An abstract data type, or ADT, is a well-defined and complete data abstraction that uses the information-hiding principle. ADTs make it possible to create and manipulate objects in a natural manner. 数据抽象就是对信息表达并对信息执行的操作。抽象数据类型(ADT)按照信息屏蔽的原则，对数据抽象作意义明确完整的定义。ADT允许用自然的方法创建和管理对象。

  2. 7.1 INTRODUCING ABSTRACT DATA TYPES抽象数据类型简介 • Fundamental-type 基本数据类型 • Data abstraction 数据抽象 • Information-hiding 信息隐蔽 • Abstract data type(ADT) 抽象数据类型 Example, an Rational ADT : Rational a ( 1, 2 ) ; // a = 1 / 2 Rational b ( 2, 3 ) ; // b = 2 / 3 cout << a << “+” << b << “=” << ( a + b) << endl ;

  3. Addition: • Mulitiplication: • Subtraction: • Division: 7.2 RATIONAL ADT BASICS有理数 Rational ADT 的基础 Our goal in developing Rational is to create a type whose objects are as natural to use as objects defined using the fundamental types. The basic arithmetic operations :

  4. Class Rational • Data members: • numerator int object • denominator int object • Member functions: • Construct the rational number with default or particular attributes. • Add, subtract, multiply, and divide the rational number to another rational • number. • Copy the value of the rational number to another rational number. • Compare the rational number to another rational number. • Display the value of the rational number. • Extract the value of the rational number. • Inspect the values of the numerator and the denominator. • Set the values of the numerator and the denominator.

  5. Rule minimality ( 最小化规则 ) • This rule states that unless a behavior is needed, it should not be part of • the ADT. • A corollary to the rule of minimality is the class minimality principle.

  6. 7.2.1 A client program using the rational library // Program 8.1 Demonstrate Rational ADT #include <iostream> #include <string> #include "rational.h" using namespace std ; int main() { Rational r , s ; cout << "Enter rational number (a/b): " ; cin >> r ; cout << "Enter rational number (a/b): " ; cin >> s ; Rational t ( r ) ; Rational Sum = r + s ; Rational Product = r * s ; cout << r << " + " << s << " = " << Sum << endl ; cout << r << " * " << s << " = " << Product << endl ; return 0; }

  7. 7.2.1 A client program using the rational library // Program 8.1 Demonstrate Rational ADT #include <iostream> #include <string> #include "rational.h" using namespace std ; int main() { Rational r , s ; cout << "Enter rational number (a/b): " ; cin >> r ; cout << "Enter rational number (a/b): " ; cin >> s ; Rational t ( r ) ; Rational Sum = r + s ; Rational Product = r * s ; cout << r << " + " << s << " = " << Sum << endl ; cout << r << " * " << s << " = " << Product << endl ; return 0; } Use the default constructor for the class Rational

  8. 7.2.1 A client program using the rational library // Program 8.1 Demonstrate Rational ADT #include <iostream> #include <string> #include "rational.h" using namespace std ; int main() { Rational r , s ; cout << "Enter rational number (a/b): " ; cin >> r ; cout << "Enter rational number (a/b): " ; cin >> s ; Rational t ( r ) ; Rational Sum = r + s ; Rational Product = r * s ; cout << r << " + " << s << " = " << Sum << endl ; cout << r << " * " << s << " = " << Product << endl ; return 0; } Use the copy constructor to create a new object.

  9. 7.2.1 A client program using the rational library // Program 8.1 Demonstrate Rational ADT #include <iostream> #include <string> #include "rational.h" using namespace std ; int main() { Rational r , s ; cout << "Enter rational number (a/b): " ; cin >> r ; cout << "Enter rational number (a/b): " ; cin >> s ; Rational t ( r ) ; Rational Sum = r + s ; Rational Product = r * s ; cout << r << " + " << s << " = " << Sum << endl ; cout << r << " * " << s << " = " << Product << endl ; return 0; } • copy constructor • The copy constructor has a single constant • reference parameter. • The copy constructor is always present : • It can be specified by designer • or is automatically supplied by the compiler.

  10. 7.2.1 A client program using the rational library // Program 8.1 Demonstrate Rational ADT #include <iostream> #include <string> #include "rational.h" using namespace std ; int main() { Rational r , s ; cout << "Enter rational number (a/b): " ; cin >> r ; cout << "Enter rational number (a/b): " ; cin >> s ; Rational t ( r ) ; Rational Sum = r + s ; Rational Product = r * s ; cout << r << " + " << s << " = " << Sum << endl ; cout << r << " * " << s << " = " << Product << endl ; return 0; } They use the copy constructor too.

  11. 7.2.1 A client program using the rational library // Program 8.1 Demonstrate Rational ADT #include <iostream> #include <string> #include "rational.h" using namespace std ; int main() { Rational r , s ; cout << "Enter rational number (a/b): " ; cin >> r ; cout << "Enter rational number (a/b): " ; cin >> s ; Rational t ( r ) ; Rational Sum = r + s ; Rational Product = r * s ; cout << r << " + " << s << " = " << Sum << endl ; cout << r << " * " << s << " = " << Product << endl ; return 0; } • Supply initialization parameters: • The parameter list. • The initialization expression.

  12. 7.2.1 A client program using the rational library // Program 8.1 Demonstrate Rational ADT #include <iostream> #include <string> #include "rational.h" using namespace std ; int main() { Rational r , s ; cout << "Enter rational number (a/b): " ; cin >> r ; cout << "Enter rational number (a/b): " ; cin >> s ; Rational t ( r ) ; Rational Sum = r + s ; Rational Product = r * s ; cout << r << " + " << s << " = " << Sum << endl ; cout << r << " * " << s << " = " << Product << endl ; return 0; } Overloaded operators

  13. 7.2.1 A client program using the rational library Assignment operator and copy construction Rational v ( 6, 21 ) ; // v is 6 / 21 Rational w ; // w is 0 / 1 w = v ; // w is 6 / 21 by assignment Rational x = v ; // x is 6 / 21 by copy construction Overloaded construction Rational x ( 3, 4 ) ; // v is 3 / 4 Rational y ( 5 ) ; // y is 5 / 1

  14. 7.2.1 A client program using the rational library const object // the data members can not be modified const Rational OneHalf ( 1, 2 ) ; Overloaded operators >> and << Rational r ; cout << "Enter rational number (a/b): " ; cin >> r ; cout << r ;

  15. 7.2.1 A client program using the rational library • If operator >> (or <<) is overloaded to be a member function, • left operand must be an object of Rational type : • Rational :: istream & operator >> ( istream &sin ) ; • Rational :: ostream & operator << ( ostream &sout ) ; • r >> cin ; • r << cout ; • If they overloaded to be common function or friend function, • we are free to define their left and right operands. • istream & operator >> ( istream &sin, const Rational &r ) ; • ostream & operator << ( ostream &sout, const Rational &r ) ; • cin >>r ; • cout << r ; const object // the data members can not be modified const Rational OneHalf ( 1, 2 ) ; Overloaded operators >> and << Rational r ; cout << "Enter rational number (a/b): " ; cin >> r ; cout << r ;

  16. Function name 7.2.1 A client program using the rational library • Operators +, * are overloaded to be common function or friend function • Member function • Rational :: Rational operator + ( const Rational &r ) ; • Rational u ( 3, 4 ) , t ; • t = u + 2 ; // OK • t = 2 + u ;// Error • Common function or friend function • Rational operator + ( const Rational &r , const Rational &s ) ; • t = u + 2 ; // OK • t = 2 + u ; // OK

  17. 7.3 RATIONAL INTERFACE DESCRIPTION // rational.h: declaration of Rational ADT #ifndef RATIONAL_H #define RATIONAL_H #include <iostream> #include <string> using namespace std; // … #endif

  18. // Rational ADT: class description class Rational { public: Rational(); // member functions default constructor Rational(int numer, int denom = 1); // a second constructor // some arithmetic and stream facilitators Rational Add(const Rational &r) const; Rational Multiply(const Rational &r) const; void Insert(ostream &sout) const; void Extract(istream &sin); protected: // inspectors int GetNumerator() const; int GetDenominator() const; // mutators void SetNumerator(int numer); void SetDenominator(int denom); private: // data members int NumeratorValue; int DenominatorValue; };

  19. // Rational ADT: auxiliary operator description Rational operator+(const Rational &r, const Rational &s); Rational operator*(const Rational &r, const Rational &s); ostream& operator<<(ostream &sout, const Rational &s); istream& operator>>(istream &sin, Rational &r); #endif

  20. 7.3.1 Access restrictions 访问权限 publiccan be directly used protected can be use by other member functions of the class and by member functions from a derived class. private can be use only by other member functions of the class .

  21. 7.3.2 Constructor member functions The prototypes of the two Rational constructors Rational(); Rational(int numer, int denom = 1); A copy constructor and a member assignment operator are defaulted, the Rational class uses the definitions provided by the compiler.

  22. 7.3.3 Facilitator member functions 简化器 • Member functions: • Inspector functions（检查器） • provide methods to access representations of the date member. • Mutator functions（转变器） • provide methods to modify the representations of the data members. • Facilitator functions（简化器） • provide methods for achieving the operations intended with the object.

  23. 7.3.3 Facilitator member functions 简化器 Rational Add ( const Rational &r ) const ; Rational Multiply ( const Rational &r ) const ; void Insert ( ostream &sout ) const ; void Extract ( istream &sin ) ;

  24. 7.3.3 Facilitator member functions 简化器 Rational Add ( const Rational &r ) const ; Rational Multiply ( const Rational &r ) const ; void Insert ( ostream &sout ) const ; void Extract ( istream &sin ) ; • Const member functions can not change any of the invoking object’s data member. • Const member functions and operators can be used by const and non-const objects. • Non-const member functions con not be used by const objects.

  25. 7.3.3 Facilitator member functions 简化器 Rational Add ( const Rational &r ) const ; Rational Multiply ( const Rational &r ) const ; void Insert ( ostream &sout ) const ; void Extract ( istream &sin ) ; For example const Rational OneHalf ( 1, 2 ) ; OneHalf . Insert ( cout ) ; // legal OneHalf . Extract ( cin ) ;// illegal, Extract() is not const member function

  26. Use the four Rational facilitators Rational r ; Rational s ; cout << "Enter rational number (a/b): " ; r.Extract ( cin ) ; cout << "Enter rational number (a/b): " ; s.Extract ( cin ) ; Rational t ( r ) ; Rational Sum = r.Add (s) ; Rational Product = r.Multiply (s) ; r.Inseral ( cout ) ; cout << " + " ; s.Inseral ( cout ) ; cout << " = " ; s.Inseral ( cout ) ; cout << endl ; r.Inseral ( cout ) ; cout << " * " ; s.Inseral ( cout ) ; cout << " = " ; Product.Inseral ( cout ) ; cout << endl ;

  27. Use the four Rational facilitators Rational r ; Rational s ; cout << "Enter rational number (a/b): " ; r.Extract ( cin ) ; cout << "Enter rational number (a/b): " ; s.Extract ( cin ) ; Rational t ( r ) ; Rational Sum = r.Add (s) ; Rational Product = r.Multiply (s) ; r.Inseral ( cout ) ; cout << " + " ; s.Inseral ( cout ) ; cout << " = " ; s.Inseral ( cout ) ; cout << endl ; r.Inseral ( cout ) ; cout << " * " ; s.Inseral ( cout ) ; cout << " = " ; Product.Inseral ( cout ) ; cout << endl ; use Overloaded operators

  28. Use the four Rational facilitators Rational r ; Rational s ; cout << "Enter rational number (a/b): " ; r.Extract ( cin ) ; cout << "Enter rational number (a/b): " ; s.Extract ( cin ) ; Rational t ( r ) ; Rational Sum = r.Add (s) ; Rational Product = r.Multiply (s) ; r.Inseral ( cout ) ; cout << " + " ; s.Inseral ( cout ) ; cout << " = " ; s.Inseral ( cout ) ; cout << endl ; r.Inseral ( cout ) ; cout << " * " ; s.Inseral ( cout ) ; cout << " = " ; Product.Inseral ( cout ) ; cout << endl ; cin >> r ; cin >> s ; Rational Sum = r + s; Rational Product = r * s; cout << r << " + " << s << " = " << Sum << endl; cout << r << " * " << s << " = " << Product << endl;

  29. Use the four Rational facilitators Rational r ; Rational s ; cout << "Enter rational number (a/b): " ; r.Extract ( cin ) ;// cin >> r ; cout << "Enter rational number (a/b): " ; s.Extract ( cin ) ; // cin >> s ; Rational t ( r ) ; Rational Sum = r.Add (s) ;// Rational Sum = r + s; Rational Product = r.Multiply (s) ;// Rational Product = r * s; r.Inseral ( cout ) ; cout << " + " ; s.Inseral ( cout ) ; cout << " = " ; s.Inseral ( cout ) ; cout << endl ; // cout << r << " + " << s << " = " << Sum << endl; r.Inseral ( cout ) ; cout << " * " ; s.Inseral ( cout ) ; cout << " = " ; Product.Inseral ( cout ) ; cout << endl ; // cout << r << " * " << s << " = " << Product << endl;

  30. 7.3.4 Inspector member function 检查器 protected: int GetNumerator() const; int GetDenominator() const;

  31. 7.3.5 Mutator member function 转变器 protected: void SetNumerator(int numer); void SetDenominator(int denom);

  32. 7.3.6 Data member 数据成员 private: int NumeratorValue ; int DenominatorValue ;

  33. 7.3.6 Overloaded operators 运算符重载 Rational operator+(const Rational &r, const Rational &s); Rational operator*(const Rational &r, const Rational &s); ostream& operator<<(ostream &sout, const Rational &s); istream& operator>>(istream &sin, Rational &r); Overloaded operators are the same as their conventional precedence and calling form . Exercise P423-12

  34. 7.4 IMPLEMENTING THE RATIONAL CLASS SCOPE OPERATOR (作用域运算符) void Rational :: SetNumerator(int numer) { NumeratorValue = numer; }

  35. 7.4.1 Constructor definitions // default constructor Rational::Rational() { SetNumerator(0); SetDenominator(1); } // (numer, denom) constructor Rational::Rational(int numer, int denom) { SetNumerator(numer); SetDenominator(denom); }

  36. 7.4.1 Constructor definitions // default constructor Rational::Rational() { SetNumerator(0); SetDenominator(1); } // (numer, denom) constructor Rational::Rational(int numer, int denom) { SetNumerator(numer); SetDenominator(denom); } Use member functions

  37. 7.4.1 Constructor definitions // default constructor Rational::Rational() { NumeratorValue = 0; DenominatorValue = 1; // (numer, denom) constructor Rational::Rational(int numer, int denom) { NumeratorValue = numer; if (denom != 0) DenominatorValue = denom; else DenominatorValue = 1; } // default constructor Rational::Rational() { SetNumerator(0); SetDenominator(1); } // (numer, denom) constructor Rational::Rational(int numer, int denom) { SetNumerator(numer); SetDenominator(denom); }

  38. 7.4.2 Inspector definitions // get the numerator int Rational::GetNumerator() const { return NumeratorValue; } // get the denominator int Rational::GetDenominator() const { return DenominatorValue; }

  39. 7.4.3 Mutator definitions // set the numerator void Rational :: SetNumerator(int numer) { NumeratorValue = numer; } // set the denominator void Rational :: SetDenominator(int denom) { if (denom != 0) { DenominatorValue = denom; } else { cerr << "Illegal denominator: " << denom<< "using 1" << endl; DenominatorValue = 1; } } Exception handling

  40. 7.4.4 Arithmetic facilitator definitions // adding Rationals Rational Rational::Add(const Rational &r) const { int a = GetNumerator(); int b = GetDenominator(); int c = r.GetNumerator(); int d = r.GetDenominator(); return Rational(a*d + b*c, b*d); } // multiplying Rationals Rational Rational::Multiply(const Rational &r) const { int a = GetNumerator(); int b = GetDenominator(); int c = r.GetNumerator(); int d = r.GetDenominator(); return Rational(a*c, b*d); } Rational x ( 1, 2 ) ; Rational y ( 1, 3 ) ; Rational z = x . Add ( y ) ; // 1/2 + 1/3 is 5/6 cout << z <<endl;

  41. 7.4.5 Insertion and extraction definitions Can you Output the value of x+y directly ? // inserting a Rational void Rational::Insert(ostream &sout) const { sout << GetNumerator() << '/' << GetDenominator(); return; } // extracting a Rational void Rational::Extract(istream &sin) { int numer; int denom; char slash; sin >> numer >> slash >> denom; SetNumerator(numer); SetDenominator(denom); return; } Rational x ; x . Extract ( cin ) ; Rational y ( 1, 3 ) ; Rational z = x . Add ( y ) ; z . Insert ( cout ) ;

  42. 7.4.5 Auxiliary arithmetic operator definitions // adding Rationals Rational operator+(const Rational &r, const Rational &s) { return r . Add ( s ) ; // is r + s } // multiplying Rationals Rational operator*(const Rational &r, const Rational &s) { return r . Multiply ( s ) ; // is r * s } Rational x ; x . Extract ( cin ) ; Rational y ( 1, 3 ) ; Rational z = x + y ; z . Insert ( cout ) ;

  43. 7.4.6 Auxiliary stream operator definitions // inserting a Rational ostream& operator<<(ostream &sout, const Rational &r) { r.Insert(sout); return sout; } // extracting a Rational istream& operator>>(istream &sin, Rational &r) { r.Extract(sin); return sin; } Rational x ; cin >> x ; Rational y ( 1, 3 ) ; Rational z = x + y ; cout << z << endl ;

  44. 7.5 COPY CONSTRUCTION, MEMBER ASSIGNMENT, AND DESTRUCTION // Rational : copy constructor Rational :: Rational ( const Rational &r ) { int a = r . GetNumerator() ; inr b = r . GetDenominator() ; SetNumerator(a) ; SetDenominator(b) ; } // Rational destructor Rational :: ~Rational ( ) { /* no body needed */ } Shallow copying (浅拷贝) The source’s data members are copied bit by bit to the corresponding data members of the target.

  45. 7.5 COPY CONSTRUCTION, MEMBER ASSIGNMENT, AND DESTRUCTION // Rational : copy constructor Rational :: Rational ( const Rational &r ) { int a = r . GetNumerator() ; inr b = r . GetDenominator() ; SetNumerator(a) ; SetDenominator(b) ; } // Rational destructor Rational :: ~Rational ( ) { /* no body needed */ } • Destructor • Cannot take a parameter. • Cannot produce a return value. • A class to a single destructor.

  46. 7.5 COPY CONSTRUCTION, MEMBER ASSIGNMENT, AND DESTRUCTION // Rational : assignment operator Rational & Rational :: operator= ( const Rational &r ) { int a = r . GetNumerator() ; inr b = r . GetDenominator() ; SetNumerator(a) ; SetDenominator(b) ; return *this ; }

  47. Object . mf actual parameter ClassType :: mf formal parameter this About thispointer • this is a key word • this is a address of the object whose member function is being invoked. • this is imparted to the member function when is being invoked by system.

  48. Object . mf actual parameter ClassType :: mf formal parameter this this &Object DM: FM: Object About thispointer • this is a key word • this is a address of the object whose member function is being invoked. • this is imparted to the member function when is being invoked by system. &Object Outside Inside Object *this Object.dm (*this).dm this->dm Object.fm (*this).fm this->fm * this

  49. #include<iostream> #include<string> using namespace std; string s="w"; class C { public: C() //defual constructor { name=s; cout<<name<<": default constructed"<<endl; } C(const C &c) //copy constructor { name=s; cout<<name<<": copy constructor using "<<c.name<<endl; } ~C() // destructor { cout<<name<<": destructed "<<endl; } C & operator=(const C &c) // assignment { cout<<name<<": assigned using "<<c.name<<endl; return *this; } private: string name; //data member }; int main(){ C w; s="x"; C x; { s = "y" ; C y ; } s = "z" ; C z(w) ; x = w = z ; return 0 ; } w: default constructed x: default constructed y: default constructed y: destructed z : copy constructor using w w: assigned using z x : assigned using w z: destructed x: destructed w: destructed

More Related