6.2 Special Operator Overloading 1

cout << c c = ++d; cout << c
<< endl << d << endl; << endl << d << endl; << endl << d << endl;
two-dimensional array
arr[rows][cols] 总行数 总列
i
arr[i][j]
rows
rows-1
j 0
cols-1
a
按行存储结构
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SEI
Overloading the Function Call Operator
intTwoArray b(3, 4); class intTwoArray { public: b(0, 1) = 10; int& operator( )( int,int ); int m = b(1, 2); const int& operator( )( int,int ) const; intTwoArray( int s1, int s2 ); int get_rows( ) const { return rows; } int get_cols( ) const { return cols; } private: int rows, cols; int *a; int& intTwoArray::operator( )(int i, int j){ }; if( i < 0 || i >= rows ) throw( "FirstOutOfBound" ); if( j < 0 || j >= cols ) throw( "SecondOutOfBount" ); return a[ i * cols + j ]; }
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Overloading the Assignment Operator
拷贝构造函数和赋值操作符都可实现对象拷贝： The copy constructor copies a class object to a new object; The assignment operator copies a class object to an already existing object. Complex c1;
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Content
Overloading the Input and Output Operators Overloading the Assignment Operator Overloading Some Special Operators Sample Application: An Associative Array Memory Management Operators
class intArray { public: int& operator[ ]( int ); const int& operator[ ] ( int ) const; intArray( int s ); int get_size( ) const { return size; } //…… intArray array( 5 ); private: for( int i = 0; i < array.get_size; i++ ) int size; array[i] = i; int* a; }; int& intArray :: operator[ ] ( int i ) { if( i < 0 || i >= size ) // 数组下标越界检查 throw string( "OutOfBounds" ); return a[i]; } //……
语法占位符，表示自增/自减 运算符的后缀形式
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Overloading the Increment/Decrement Operators
实现能够完成以下输出的时钟类Clock：
Clock c, d(1, 30, 1);
11:59 AM 1:30 PM 1:31 PM 1:31 PM 1:31 PM 1:32 PM
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Overloading the Function Call Operator ( )
The function call operator ( ) must be overloaded as a method. Its declaration looks like:
class C { //……
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Operator Overloading
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PowerPoint Presentation for LiuHui, Object-Oriented Programming for C++, 2nd Edition Copyright 2007 © SEI, All rights reserved.
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SEI
Overloading The Input and Output Operators
template <class E, class T = char_traits<E> > class basic_istream : virtual public basic_ios<E, T> {（右移） public: //…… basic_istream& operator>> ( bool& n ); int i; double d; basic_istream& operator>> ( short& n ); basic_istream& operator>> ( unsigned short& n ); cin >> i; cin >> d; basic_istream& operator>> ( int& n ); basic_istream& operator>> ( unsigned int& n ); basic_istream& operator>> ( long& n ); basic_istream& operator>> ( unsigned long& n ); basic_istream& operator>> ( void *& n ); basic_istream& operator>> ( float& n ); basic_istream& operator>> ( double& n ); basic_istream& operator>> ( long double& n ); //…… };
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Overloading the Subscript Operator [ ]
The subscript operator [ ] （下标运算符）must be overloaded as a method. Its declaration typically looks like
class C {
The system overloads the right-shift for formatted input of built-in types as a method in appropriate system class.
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Overloading The Input and Output Operators
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SEI
Overloading the Increment/Decrement Operators
重载方式：
通常以成员函数形式重载 class C { returntype returntype returntype returntype // ... ... }; operator＋＋ ( ); operator－－( ); operator＋＋( int ); operator－－( int );
}; class Complex { // 复数类 istream& operator>> ( istream& in, Complex& c ) { double real, return in >> c.real >> c.imag; imag; } //…… Complex c1; }; cin >> c1; Complex c1; cin >> c1;
returntype operator( ) ( paramtypes );
//…… }
paramtypes is the list of parameter types separated by commas
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SEI
Overloading the Function Call Operator
Object-Oriented Programming
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PowerPoint Presentation for LiuHui, Object-Oriented Programming for C++, 2nd Edition Copyright 2007 © SEI, All rights reserved.
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SEI
Overloading Some Special Operators