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高等程式語言實習課. http://helldeathscythe.myweb.hinet.net/. Operator overloading. 在 C++ 語言中, << 運算符號可以配合 cout 作為字串資料流輸出符號,同樣也可以作為左移位元運算符號 + - 可以作為數字的正負,也可以作為加法與減法的運算符號 因為它們都被超載 (overloading) 在 C++ 的類別資料庫中. Operator overloading. 使用者自訂的類別. 原始版 理想版. void main() { frac f1(1,2),f2(1,3),f3;

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高等程式語言實習課


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    1. 高等程式語言實習課

    2. http://helldeathscythe.myweb.hinet.net/

    3. Operator overloading • 在C++語言中,<<運算符號可以配合cout作為字串資料流輸出符號,同樣也可以作為左移位元運算符號 • + - 可以作為數字的正負,也可以作為加法與減法的運算符號 • 因為它們都被超載(overloading)在C++的類別資料庫中

    4. Operator overloading • 使用者自訂的類別 原始版 理想版 void main() { frac f1(1,2),f2(1,3),f3; if(f1.bigger(f2)) f3.copy(f1.sub(f2)); else f3.copy(f1.add(f2)); f3.print(); } void main() { frac f1(1,2),f2(1,3),f3; if(f1>f2) f3=f1-f2; else f3=f1+f2; f3.print(); } Of course Why not?

    5. Operator overloading • 二元運算子 • 算數符號: = + - * / += -= • 關係符號: > < >= <= == != • 邏輯符號: && || &(and) |(or) ^(xor) • IO: << >> • 一元運算子 • ++ -- + - • 其他 • new delete -> [] () ,

    6. Operator overloading class ClassName { ... //超載運算子X,可能是+-/*... return_type operatorX(...) { ... } };

    7. Operator overloading 原始版 運算子超載 class point{ int x,y;public: ...//建構子等其他函數point add(const point &p2){ return point(x+p2.x,y+p2.y); //匿名物件} void set(const point &p2){ this->x = p2.x; this->y = p2.u; } }; class point{ int x,y; public: ...//建構子等其他函數 point operator+(const point &p2){ point p(x+p2.x,y+p2.y); retrun p; } void operator=(const point &p2){ x = p2.x; y = p2.u; } };

    8. Operator overloading p1+p2; p1=p2; p3=p1+p2; if (p1>p2) p1=p2; else p2=p1; p1.operato+(p2); p1.operator=(p2); p3.operator=(p1.operator+(p2)); if(p1.operator>(p2)) p1.operator=(p2); else p2.operator=(p1);

    9. Operator overloading • 這是什麼? p3.operator+(p1.operator-(p2)); p1.operator+(p2.operator*(p3)); p3.operator+(p2.operator*(p1)); p1.operator=(p2.operator=(p3)); f1.operator=(p2.operator[](1)); p1.operator++(); p1.operator+(2); p3+p1-p2; p3+p2*p1; p2*p1+p3; p1=p2=p3; f1=p2[1]; p1++; p1+2; ?

    10. *Operator overloading • 細談operator=() • 當類別含有指標成員時一定要 • 建構子 Copy Constructor • 超載 Operator =(); • 解構子Destructor

    11. 0 1 2 3 4 5 *Operator overloading List L1 = List L2 Int* A Int* A 0X001125 0X001125

    12. 0 0 1 1 2 2 3 3 4 4 5 5 *Operator overloading List L1 = List L2 Int* A Int* A 0X001125 0X001256

    13. *Operator overloading • operator=()的程式步驟 • x1 == x1 ? • x1陣列長度 = x2陣列長度 ? • delete x1; • x1 = new type[x2.size()]; • 複製x2 to x1 • return *this;

    14. Operator overloading • ++前置與後置 class point{ int x,y;public: ... point& operator++(){ //前置prefix ++i ++x; ++y; retrun *this; } point operator++(int){ //後置postfix i++; point p(*this); x++; y++; return p; }};

    15. Operator overloading • -(負號)的超載 class point{ int x,y;public: ... point& operator-(){ return point(-x,-y); }}; 如果-(負號)與-(減法)同時被超載,執行時會不會搞混?

    16. 更多的Operator overloading? • Friend Operator functions • Type Operator functions

    17. Friend Operator functions • 這是什麼? ? p1+2; 2+p1; p1.operator+(2); 2.operator+(p1); // ???

    18. Friend Operator functions • 提供一個兩個參數的operator+ class point{ int x,y; ...};point operator+(const point& p1,const point& p2){ ...//寫什麼?}int main(){ point p1(3,5),p2(4,7),p3; p3=p1+p2; p3=5+p1;} 注意: 由於point沒有實作operator+ p1+p2才會被編譯成operator+(p1,p2) 5+p1會被編譯成operator+(point(5)+p2);

    19. Friend Operator functions • 提供一個兩個參數的operator+ class point{ int x,y; friend point operator+(const point& p1,const point& p2);};point operator+(const point& p1,const point& p2){ retrun point(p1.x+p2.x,p1.y+p2.y);}int main(){ point p1(3,5),p2(4,7),p3; p3=p1+p2; p3=5+p1;} 你是我的朋友,所以你的東西就是我的東西!?

    20. Type Operator functions • 資料型態也可以超載 class clock{ int h,m,s; ...};void mian(){ clock c(17,32,43); int sec = int( c ); //17*3600+32*60+43 Cout << sec;}

    21. Type Operator functions • 資料型態也可以超載 class clock{ int h,m,s; operator int() { return h*3600+m*60+s; }};void mian(){ clock c(17,32,43); int sec = c; //17*3600+32*60+43 Cout << sec;}