Array Class Printout of the array - c++

Question

I am trying to create a member function which print out the array that I control, but I am running into Seg fault. Any help would be really useful!
Here is my header file, all the code in there work except the last member function.
#include <iostream>
#include <assert.h>
using namespace std;
#ifndef _ARRAY_H
#define _ARRAY_H
template<class T>
class Array{
private:
T *a;
int length;
public:
// constructor
Array (int len){
length = len;
a = new T[length];
for (int i = 0; i < len; i++){
a[i]=0;
}
}
// destructor
~Array()
{delete[] a;}
// operator overload
T& operator [](int i){
assert (i>=0 && i < length);
return a[i];
}
// operator overload
Array<T>& operator=(Array<T> &b){
if (a !=nullptr) delete[] a;
a = b.a;
b.a = nullptr;
length = b.length;
return *this;
}
//get the length of the array
int arraylength(){
return length;
}
//------------------This below is where I am having issue --------//
//print out the array
Array<T> printarray(){
for (int i = 0; i < length; i++){
cout << a[i];
}
}
};
int main();
#endif
This is my main file
#include <iostream>
#include "../include/array.h"
using namespace std;
int main(){
// initialize array
Array <int> a(5);
Array <int> b(5);
// put stuff into array
for (int i = 0; i< a.arraylength(); i++){
a[i] = i;
}
// set b = a using operator overload
b = a;
// print out the result b array
for (int i = 0; i < b.arraylength(); i++){
cout << b[i] << endl;
}
a.printarray();
return 0;
}
Again. Thank you for the help, I am quite new to C++ and mostly self taught.

Answer 1

In this statement
b = a;
you have called operator= in which a pointer of a object was set to nullptr, but in printArray you don't check if a is not null, so you are accesing data for null pointer, it is undefined behaviour. Add the condition to check if array is not empty:
void printarray(){
if (!a) return; // <- array is empty
for (int i = 0; i < length; i++){
cout << a[i];
}
}
Secondly, return type of printArray should be void, you don't return any value in this function.

Answer 2

You should fix printarray by changing the return type to void and making it a const member function.
void printarray() const {
for (int i = 0; i < length; i++){
cout << a[i];
}
}
However, that is not the main problem in your code. The main problem is that you are not following the The Rule of Three.
You don't have copy constructor.
You have a copy assignment operator but it is not implemented properly.
The line
b = a;
causes problems downstream that can be fixed by following The Rule of Three.
Here's an implementation of the copy assignment operator function that should work.
// Make the RHS of the operator a const object.
Array<T>& operator=(Array<T> const& b)
{
// Prevent self assignment.
// Do the real assignment only when the objects are different.
if ( this != &b )
{
if (a != nullptr)
{
delete[] a;
a = nullptr;
}
// This is not appropriate.
// a = b.a;
// b.a = nullptr;
// b needs to be left untouched.
// Memory needs to be allocated for this->a.
length = b.length;
if ( length > 0 )
{
a = new T[length];
// Copy values from b to this.
for (int i = 0; i < length; ++i )
{
a[i] = b.a[i];
}
}
}
return *this;
}
Please note that you should implement the copy constructor also, and then use the copy swap idiam to implment the assignment operator.
Very relevant: What is the copy-and-swap idiom?