如何在C ++中写一个简单的类？

问题描述

我一直在阅读很多关于C ++类的教程，但他们错过了其他教程包括的内容。

I have been reading a lot of tutorials on C++ class but they miss something that other tutorials include.

有人可以告诉我如何写和使用一个非常简单的C ++类使用可见性，方法和一个简单的构造函数和析构函数？

Can someone please show me how to write and use a very simple C++ class that uses visibility, methods and a simple constructor and destructor?

推荐答案

href =http://www.java-samples.com/showtutorial.php?tutorialid=313> C ++中的构造函数和析构函数：

welll documented example taken and explained better from Constructors and Destructors in C++:

#include <iostream>      // for cout and cin

class Cat                   // begin declaration of the class
{
  public:                    // begin public section
    Cat(int initialAge);     // constructor
    Cat(const Cat& copy_from); //copy constructor
    Cat& operator=(const Cat& copy_from); //copy assignment
    ~Cat();                  // destructor

    int GetAge() const;            // accessor function
    void SetAge(int age);    // accessor function
    void Meow();
 private:                   // begin private section
    int itsAge;              // member variable
    char * string;
};

 // constructor of Cat,
Cat::Cat(int initialAge)
{
  itsAge = initialAge;
  string = new char[10]();
}

//copy constructor for making a new copy of a Cat
Cat::Cat(const Cat& copy_from) {
   itsAge = copy_from.itsAge;
   string = new char[10]();
   std::copy(copy_from.string+0, copy_from.string+10, string);
}

//copy assignment for assigning a value from one Cat to another
Cat& Cat::operator=(const Cat& copy_from) {
   itsAge = copy_from.itsAge;
   std::copy(copy_from.string+0, copy_from.string+10, string);
}

Cat::~Cat()                 // destructor, just an example
{
    delete[] string;
}

// GetAge, Public accessor function
// returns value of itsAge member
int Cat::GetAge() const
{
   return itsAge;
}

// Definition of SetAge, public
// accessor function

 void Cat::SetAge(int age)
{
   // set member variable its age to
   // value passed in by parameter age
   itsAge = age;
}

// definition of Meow method
// returns: void
// parameters: None
// action: Prints "meow" to screen
void Cat::Meow()
{
   cout << "Meow.\n";
}

// create a cat, set its age, have it
// meow, tell us its age, then meow again.
int main()
{
  int Age;
  cout<<"How old is Frisky? ";
  cin>>Age;
  Cat Frisky(Age);
  Frisky.Meow();
  cout << "Frisky is a cat who is " ;
  cout << Frisky.GetAge() << " years old.\n";
  Frisky.Meow();
  Age++;
  Frisky.SetAge(Age);
  cout << "Now Frisky is " ;
  cout << Frisky.GetAge() << " years old.\n";
  return 0;
}

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