C++读书笔记之 赋值运算符= 重载 前缀自减运算符--重载 求负运算符- 重载

/**重载赋值运算符 = **/
      void operator=(const Distance &D )
      {
         feet = D.feet;
         inches = D.inches;
      }
      /**重载负号运算符 -  **/
        Distance operator-()
      {
         feet = -feet;
         inches = -inches;
         return Distance(feet, inches);
      }
      /**重载前缀自减运算符 --  **/
        Distance operator--()
        {
            --feet;
            --inches;
            return Distance(feet, inches);
        }
         /**重载后缀自减运算符 --  **/
        Distance operator--(int)
        {
            Distance Temp(feet,inches);
            feet--;
            inches--;
            return Temp;

        }

#include <iostream>using namespace std;class Distance{   private:      double feet;             // 0 to infinite      double inches;           // 0 to 12   public:      // required constructors      Distance()      {         feet = 0.0;         inches = 0.0;      }      Distance(double f, double i)      {         feet = f;         inches = i;      }      /**重载赋值运算符 = **/      void operator=(const Distance &D )      {         feet = D.feet;         inches = D.inches;      }      /**重载负号运算符 -  **/        Distance operator-()      {         feet = -feet;         inches = -inches;         return Distance(feet, inches);      }      /**重载前缀自减运算符 --  **/        Distance operator--()        {            --feet;            --inches;            return Distance(feet, inches);        }         /**重载后缀自减运算符 --  **/        Distance operator--(int)        {            Distance Temp(feet,inches);            feet--;            inches--;            return Temp;        }      // method to display distance      void displayDistance()      {         cout << "Feet: " << feet <<  " Inches:" <<  inches << endl;      }};int  main(){    Distance D1(19.91, -20.13),D2;    cout << "\nD1 Distance now: \n";    D1.displayDistance();    --D1;    cout << "\nD1 Distance after  --D1  : \n";    D1.displayDistance();    -D1;    cout << "\nD1 Distance after  -D1  : \n";    D1.displayDistance();    cout << "\nD1--.displayDistance():\n";    D1--.displayDistance();    // use assignment operator    D2 = D1--;    cout << "\nafter D2=D1-- Distance of D2 :\n";    D2.displayDistance();    cout << "\nafter D2=D1-- Distance of D1 :\n";    D1.displayDistance();    return 0;}/**************************运行结果：D1 Distance now:Feet: 19.91 Inches:-20.13D1 Distance after  --D1  :Feet: 18.91 Inches:-21.13D1 Distance after  -D1  :Feet: -18.91 Inches:21.13D1--.displayDistance():Feet: -18.91 Inches:21.13after D2=D1-- Distance of D2 :Feet: -19.91 Inches:20.13after D2=D1-- Distance of D1 :Feet: -20.91 Inches:19.13Process returned 0 (0x0)   execution time : 0.819 sPress any key to continue.***************************/