assignoperator.cpp

《24学时精通c++》的光盘内容

 // Listing 14.6
 // Copy constructors
 #include <iostream>
 
 class CAT
 {
 public:
     CAT(); // default constructor
     // copy constructor and destructor elided!
     int GetAge() const { return *itsAge; }
     int GetWeight() const { return *itsWeight; }
     void SetAge(int age) { *itsAge = age; }
     CAT operator=(const CAT &);
 
 private:
     int *itsAge;
     int *itsWeight;
 };
 
 CAT::CAT()
 {
     itsAge = new int;
     itsWeight = new int;
     *itsAge = 5;
     *itsWeight = 9;
 }
 
 
 CAT CAT::operator=(const CAT & rhs)
 {
     if (this == &rhs)
         return *this;
     delete itsAge;
     delete itsWeight;
     itsAge = new int;
     itsWeight = new int;
     *itsAge = rhs.GetAge();
     *itsWeight = rhs.GetWeight();
     return *this;
 }
 
 
 int main()
 {
     CAT frisky;
     std::cout << "frisky's age: " << frisky.GetAge() 
         << std::endl;
     std::cout << "Setting frisky to 6...\n";
     frisky.SetAge(6);
     CAT whiskers;
     std::cout << "whiskers' age: " << whiskers.GetAge() 
         << std::endl;
     std::cout << "copying frisky to whiskers...\n";
     whiskers = frisky;
     std::cout << "whiskers' age: " << whiskers.GetAge() 
         << std::endl;
     return 0;
 }