Going through array using for_each loop in cpp - c++

Question

First off, here is the code:
#include <iostream>
#include <algorithm>
using namespace std;
class Array
{
int* arr;
int n;
public:
Array();
Array(const Array&);
Array(Array &&);
Array& operator=(const Array&);
Array& operator=(Array &&);
void print();
~Array();
};
Array::Array()
{
cout<<"No of elements: "<<endl;
cin>>n;
if(n!=0)
{
arr = new int [n];
cout<<"\nInsert values:"<<endl;
for_each(arr, arr+n, [](int x){cin>>x;});
}
}
Array::Array (const Array& a)
{
int i=0;
this->n=a.n;
arr= new int [n];
for(i=0;i<n;i++)
arr[i]=a.arr[i];
}
Array::Array (Array &&a)
{
this->n=a.n;
arr=a.arr;
a.arr=nullptr;
}
Array& Array::operator=(const Array& a)
{
int i=0;
this->n=a.n;
arr= new int [n];
for(i=0;i<n;i++)
arr[i]=a.arr[i];
return *this;
}
Array& Array::operator=(Array &&a)
{
this->n=a.n;
arr=a.arr;
a.arr=nullptr;
return *this;
}
void Array::print()
{
for_each(arr, arr+n, [](int a){cout<<a;});
}
Array::~Array()
{
n=0;
delete [] arr;
}
int main()
{
Array a;
Array b;
Array c=a;
Array d;
d=b;
c.print();
cout<<endl;
d.print();
return 0;
}
So, as you can see, i made default constructor (if constructor with no parameters can be called default) that creates an array using for_each loop with lambda function used as a third parameter, all it does, as you can see is that it accepts the values i insert and places it as a values of variable x, which should take values from arr[0] to arr[n-1].
However, when i print put any of arrays created in main, it prints out only zeroes, it is not due to copy constructors, because i tried printing arrays a and b and same thing happened (notice that in this case i am printing out c and d, as they are copies of a and b, respectively).
I also tried to see if it works properly as i tried to print out some elements of array right after for_each loop finished, and it turns out that for_each loop has no effect on the array as it stays zero even right after loop.
Any help appreciated!

Answer 1

When you're using for_each loops, you're passing a lambda,
for_each(arr, arr+n, [](int x){cin>>x;});
But the argument of the lambda (int x), mean that you're creating a copy of an array element, that you will assign a value to. That copy will be destroyed when you leave the body of the lambda, while the original value inside the array remains unchanged.
Change it to
for_each(arr, arr+n, [](int& x){cin>>x;});
That way you won't create a copy of the value inside the array, but you'll pass a reference to it, which means you will write the values into the array.