Answer to Question #326351 in C++ for khan

Question

Your goal is to overload the operators for “Array” class. You will need to write three files (array.h, array.cpp).

class Array{

// think about the private data members...

public:

Array();

Array(int size);

Array(int* arr, int size);

Array(const Array &);

int& operator[](int i); // returns int at [i] int& operator[](int i) const;

const Array & operator=(const Array&);

Array operator+(const Array&);

Array operator-(const Array&);

Array operator++();

Array operator++(int);

Array& operator--(int);

bool operator==(const Array&)const; // returns true if two arrays are same

bool operator!(); // returns true if the Array is empty

void operator+=(const Array&);

void operator-=(const Array&);

int operator()(int idx, int val); // erases the value val at idx. Returns 1 for deletion and -1 if idx does not exist or is invalid.

~Array();

};

ostream& operator<<(ostream& input, const Array&);

istream& operator>>(istream& output, Array&);

Answer 1

#include<iostream>
#include<vector>

using namespace std;


class Array
{
	vector<int>v;
public:
	Array():v(0) {};
	Array(int size) :v(size, 0) {};
	Array(int* arr, int size)
	{
		for (int i = 0; i < size; i++)
		{
			v.push_back(arr[i]);
		}
	}
	Array(const Array& a) :v(a.v) {}


	int& operator[](int i) // returns int at [i] int& operator[](int i) const
	{
		return v[i];
	}
	const Array& operator=(const Array& a)
	{
		v = a.v;
		return *this;
	}
	Array operator+(const Array& a)
	{
		Array tmp(v.size());
		for (int i = 0; i < v.size(); i++)
		{
			tmp.v[i] = v[i] + a.v[i];
		}
		return tmp;
	}
	Array operator-(const Array& a)
	{
		Array tmp(v.size());
		for (int i = 0; i < v.size(); i++)
		{
			tmp.v[i] = v[i] - a.v[i];
		}
		return tmp;
	}
	
	Array operator++()
	{
		Array tmp(v.size());
		for (int i = 0; i < v.size(); i++)
		{
			tmp.v[i] = v[i] +1;
		}
		return tmp;
	}
	Array operator+(int val)
	{
		Array tmp(v.size());
		for (int i = 0; i < v.size(); i++)
		{
			tmp.v[i] = v[i] + val;
		}
		return tmp;
	}
	Array& operator--(int)
	{
		Array tmp(v.size());
		for (int i = 0; i < v.size(); i++)
		{
			tmp.v[i] = v[i] - 1;
		}
		return tmp;
	}
		
	bool operator==(const Array& a)const // returns true if two arrays are same
	{
		if (v.size() != a.v.size())return false;
		for (int i = 0; i < v.size(); i++)
		{
			if (v[i] != a.v[i]) return false;
		}
		return true;
	}
	bool operator!() // returns true if the Array is empty
	{
		if (v.size() == 0)return true;
		else return false;
	}
	void operator+=(const Array& a)
	{
		for (int i = 0; i < v.size(); i++)
		{
			v[i] += a.v[i];
		}
	}
	void operator-=(const Array& a)
	{
		for (int i = 0; i < v.size(); i++)
		{
			v[i] -= a.v[i];
		}
	}
	int operator()(int idx, int val) // erases the value val at idx. Returns 1 for deletion and -1 if idx does not exist or is invalid.
	{
		if (v[idx] == val)
		{
			vector<int>::iterator it;
			for (it = v.begin(); it != v.end(); it++)
			{
				if (*it == val)
				{
					v.erase(it);
					break;
				}
			}
		}
	}
	~Array() {};
	friend ostream& operator<<(ostream& os, const Array&);


	friend istream& operator >> (istream& output, Array&);
};


ostream& operator<<(ostream& os, const Array& a)
{
	for (int i = 0; i < a.v.size(); i++)
	{
		os << a.v[i] << " ";
	}
	return os;
}
istream& operator >> (istream& is, Array& a)
{
	for (int i = 0; i < a.v.size(); i++)
	{
		is>>a.v[i];
	}
	return is;
}


int main()
{
	Array a(5);
	cout << "Enter values of an array: ";
	cin >> a;
	cout << "Third of an array: ";
	cout << a[2] << endl;
	int arr[5] = { 1,2,3,4,5 };
	Array b(arr, 5);
	cout << b<<endl;
	cout << b+5 << endl;
	cout << a +b << endl;
	cout << a -b << endl;
	a += b;
	cout << a << endl;
	a -= b;
	cout << a << endl;


}