模板类与运算符重载

标签：c++

我自定义了一个模板类并重载了运算符，预定义实现功能为能实现对数组一般操作，类似于vector。

#ifndef ARRAY_H
#define ARRAY_H

#include <iostream>
using namespace std;


template<class T>
class Array{
	friend ostream& operator<<(ostream&, const Array &);
	friend istream& operator>>(istream&, Array &);
public:
	Array(int arraySize = 10){
		size = (arraySize > 0 ? arraySize : 10);
		ptr = new T[size];
		for (int i = 0; i < size; i++)
			ptr[i] = 0;

	}
	Array(const Array  &arrayToCopy){
		ptr = new int[size];

		for (int i = 0; i < size; i++){
			ptr[i] = arrayToCopy[i];
		}
	}



	~Array(){
		delete[] ptr;
	}

	int getSize()const{
		return size;
	}

	const Array& operator=(const Array &right){
		if (&right != this){
			if (size != right.size){
				delete[] ptr;
				size = right.size;
				ptr = new T[size];
			}
			for (int i = 0; i < size; i++)
				ptr[i] = right.ptr[i];
		}
		return *this;
	}

	bool operator==(const Array &right)const{
		if (size != right.size)
			return false;

		for (int i = 0; i < size; i++)
			if (ptr[i] != right.ptr[i])
				return false;

		return true;
	}

	bool operator!=(const Array &right)const{
		return !(*this == right);
	}


	T& operator[](int subscript)
	{
		if (subscript < 0 || subscript >= size){
			cerr << "\nError: Subscript " << subscript
				<< "out of range" << endl;
			exit(1);
		}

		return ptr[subscript];
	}
	T operator[](int subscript)const{
		if (subscript < 0 || subscript >= size)
		{
			cerr << "\nError: Subscript" << subscript
				<< "out of range" << endl;
			exit(1);
		}
		return ptr[subscript];
	}

private:
	int size;
	T *ptr;
};



#endif




template<class T>
istream& operator>>(istream &input, Array<T> &a){
	for (int i = 0; i < a.size; i++)
		input >> a.ptr[i];
	return input;
}

template<class T>
ostream& operator<<(ostream &output, const Array<T> &a){
	int i;

	for (i = 0; i < a.size; i++){
		output << setw(12) << a.ptr[i];

		if ((i + 1) % 4 == 0)
			ouput << endl;
	}

	if (i % 4 != 0)
		output << endl;

	return output;
}

#include <iostream>
#include "Array.h"

using namespace std;

int main(){
	Array<int> integers1(7);

	
	cout << "Size of Array integers1 is "
		<< integers1.getSize()
		<< "\nArray after initialization:\n"<< integers1;
	
}

1>main.obj : error LNK2019: 无法解析的外部符号 "class std::basic_ostream<char,struct std::char_traits<char> > & __cdecl operator<<(class std::basic_ostream<char,struct std::char_traits<char> > &,class Array<int> const &)" (??6@YAAAV?$basic_ostream@DU?$char_traits@D@std@@@std@@AAV01@ABV?$Array@H@@@Z)，该符号在函数 _main 中被引用

没设置友元后

头文件

#ifndef ARRAY_H
#define ARRAY_H

#include <iostream>
using namespace std;


template<class T>
class Array{
	//friend ostream& operator<<(ostream&, const Array &);
	//friend istream& operator>>(istream&, Array &);
public:
	Array(int arraySize = 10){
		size = (arraySize > 0 ? arraySize : 10);
		ptr = new T[size];
		for (int i = 0; i < size; i++)
			ptr[i] = 0;

	}
	Array(const Array  &arrayToCopy){
		ptr = new int[size];

		for (int i = 0; i < size; i++){
			ptr[i] = arrayToCopy[i];
		}
	}



	~Array(){
		delete[] ptr;
	}

	int getSize()const{
		return size;
	}

	const Array& operator=(const Array &right){
		if (&right != this){
			if (size != right.size){
				delete[] ptr;
				size = right.size;
				ptr = new T[size];
			}
			for (int i = 0; i < size; i++)
				ptr[i] = right.ptr[i];
		}
		return *this;
	}

	bool operator==(const Array &right)const{
		if (size != right.size)
			return false;

		for (int i = 0; i < size; i++)
			if (ptr[i] != right.ptr[i])
				return false;

		return true;
	}

	bool operator!=(const Array &right)const{
		return !(*this == right);
	}


	T& operator[](int subscript)
	{
		if (subscript < 0 || subscript >= size){
			cerr << "\nError: Subscript " << subscript
				<< "out of range" << endl;
			exit(1);
		}

		return ptr[subscript];
	}
	T operator[](int subscript)const{
		if (subscript < 0 || subscript >= size)
		{
			cerr << "\nError: Subscript" << subscript
				<< "out of range" << endl;
			exit(1);
		}
		return ptr[subscript];
	}

private:
	int size;
	T *ptr;
};



#endif




template<class T>
istream& operator>>(istream &input, Array<T> &a){
	for (int i = 0; i < a.size; i++)
		input >> a.ptr[i];
	return input;
}

template<class T>
ostream& operator<<(ostream &output, const Array<T> &a){
	int i;

	for (i = 0; i < a.size; i++){
		output << setw(12) << a.ptr[i];

		if ((i + 1) % 4 == 0)
			ouput << endl;
	}

	if (i % 4 != 0)
		output << endl;

	return output;
}

主函数

#include <iostream>
#include "Array.h"

using namespace std;

int main(){
	Array<int> integers1(7);
	Array<int> integers2;
	Array<char> char_string(100);
	
	cout << "Size of Array integers1 is "
		<< integers1.getSize()
		<< "\nArray after initialization:\n" << endl;
	//<< integers1;

	cout << "Size of Array char_string is "
		<< char_string.getSize()
		<< "\nArray after initialization:\n" << endl;
	//<< integers1;
	
	if (integers1 != integers2)
		cout << "integers1 and integers2 are not equal" << endl;

	cout << "\ninteger2[5] is " << integers2[5] << endl;
}

运行截图

模板类与运算符重载

标签：c++

原文地址：http://blog.csdn.net/u010003835/article/details/47174127