4elist1904.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 19.4 Using Operator ostream
#include <iostream>
using namespace std;

const int DefaultSize = 10;

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

	friend ostream& operator<< (ostream&, Array<T>&);

private:
	T *pType;
	int  itsSize;
};

template <class T>
ostream& operator<< (ostream& output, Array<T>& theArray)
{
	for (int i = 0; i<theArray.GetSize(); i++)
		output << "[" << i << "] " << theArray[i] << endl;
	return output;
}

// 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;
}

int main()
{
	bool Stop = false;       // flag for looping
	int offset, value;
	Array<int> theArray;

	while (!Stop)
	{
		cout << "Enter an offset (0-9) ";
		cout << "and a value. (-1 to stop): " ;
		cin >> offset >> value;

		if (offset < 0)
			break;

		if (offset > 9)
		{
			cout << "***Please use values between 0 and 9.***\n";
			continue;
		}

		theArray[offset] = value;
	}

	cout << "\nHere's the entire array:\n";
	cout << theArray << endl;
	return 0;
}