4elist1902.cpp

《21天学通C＋＋》附盘的原代码。书上的每个例子在这里都有相应的C语言程序。

//Listing 19.2 The Implementation of the Template Array
#include <iostream>

const int DefaultSize = 10;

// declare a simple Animal class so that we can
// create an array of animals

class Animal
{
public:
	Animal(int);
	Animal();
	~Animal() {}
	int GetWeight() const { return itsWeight; }
	void Display() const { std::cout << itsWeight; }
private:
	int itsWeight;
};

Animal::Animal(int weight):
	itsWeight(weight)
{}

Animal::Animal():
	itsWeight(0)
{}


template <class T>  // declare the template and the parameter
class Array            // the class being parameterized
{
public:
	// constructors
	Array(int itsSize = DefaultSize);
	Array(const Array &rhs);
	~Array() { delete [] pType; }

	// operators
	Array& operator=(const Array&);
	T& operator[](int offSet) { return pType[offSet]; }
	const T& operator[](int offSet) const
		{ return pType[offSet]; }
	// accessors
	int GetSize() const { return itsSize; }

private:
	T *pType;
	int  itsSize;
};

// implementations follow...

// implement the Constructor
template <class T>
Array<T>::Array(int size):
itsSize(size)
{
	pType = new T[size];
	for (int i = 0; i<size; i++)
		pType[i] = 0;
}

// copy constructor
template <class T>
Array<T>::Array(const Array &rhs)
{
	itsSize = rhs.GetSize();
	pType = new T[itsSize];
	for (int i = 0; i<itsSize; i++)
		pType[i] = rhs[i];
}

// operator=
template <class T>
Array<T>& Array<T>::operator=(const Array &rhs)
{
	if (this == &rhs)
		return *this;
	delete [] pType;
	itsSize = rhs.GetSize();
	pType = new T[itsSize];
	for (int i = 0; i<itsSize; i++)
		pType[i] = rhs[i];
	return *this;
}

// driver program
int main()
{
	Array<int> theArray;      // an array of integers
	Array<Animal> theZoo;     // an array of Animals
	Animal *pAnimal;

	// fill the arrays
	for (int i = 0; i < theArray.GetSize(); i++)
	{
		theArray[i] = i*2;
		pAnimal = new Animal(i*3);
		theZoo[i] = *pAnimal;
		delete pAnimal;
	}
	// print the contents of the arrays
	for (int j = 0; j < theArray.GetSize(); j++)
	{
		std::cout << "theArray[" << j << "]:\t";
		std::cout << theArray[j] << "\t\t";
		std::cout << "theZoo[" << j << "]:\t";
		theZoo[j].Display();
		std::cout << std::endl;
	}

	return 0;
}