passconstptr.cpp

24小时攻克C++课本中的程序

 //Listing 12.2
 // Passing pointers to objects
 #include <iostream>
 
 class SimpleCat
 {
 public:
     SimpleCat();
     SimpleCat(SimpleCat&);
     ~SimpleCat();
 
     int GetAge() const { return itsAge; }
     void SetAge(int age) { itsAge = age; }
 
 private:
     int itsAge;
 };
 
 SimpleCat::SimpleCat()
 {
     std::cout << "Simple Cat Constructor...\n";
     itsAge = 1;
 }
 
 SimpleCat::SimpleCat(SimpleCat&)
 {
     std::cout << "Simple Cat Copy Constructor...\n";
 }
 
 SimpleCat::~SimpleCat()
 {
     std::cout << "Simple Cat Destructor...\n";
 }
 
 const SimpleCat * const 
 FunctionTwo (const SimpleCat * const theCat);
 
 int main()
 {
     std::cout << "Making a cat...\n";
     SimpleCat Frisky;
     std::cout << "Frisky is ";
     std::cout << Frisky.GetAge() << " years old\n";
     int age = 5;
     Frisky.SetAge(age);
     std::cout << "Frisky is ";
     std::cout << Frisky.GetAge() << " years old\n";
     std::cout << "Calling FunctionTwo...\n";
     FunctionTwo(&Frisky);
     std::cout << "Frisky is ";
     std::cout << Frisky.GetAge() << " years old\n";
     return 0;
 }
 
 // functionTwo, passes a const pointer
 const SimpleCat * const 
 FunctionTwo (const SimpleCat * const theCat)
 {
     std::cout << "Function Two. Returning...\n";
     std::cout << "Frisky is now " << theCat->GetAge();
     std::cout << " years old \n";
     // theCat->SetAge(8);   const!
     return theCat;
 }