undefined reference to Array::operator[](int)

[AL88]

Can someone help me fix the error on line 61 thanks.

#include <iostream>

const int defaultsize = 10;

class Array
{
public:
    // constructors
    Array(int itsSize = defaultsize);
    Array(const Array & rhs);
    ~Array() { delete [] pType;}
    
    // operators
    Array& operator=(const Array &);
    int& operator[] (int offset);
    const int& operator[] (int offset) const;
    
    // accessors
    int GetitsSize() const { return itsSize;}
    
    //friend function
    friend std::ostream& operator<< (std::ostream&, const Array&);
    
    // define the exception classes
    class xBoundary {};
    class xTooBig {};
    class xTooSmall {};
    class xTerm {};
    class xNegative {};
    class xZero {};
private:
    int *pType;
    int itsSize;
};

Array::Array(int size):
itsSize(size)
{
    if(size == 0)
        throw xZero();
    if(size<10)
        throw xTooSmall();
    if (size > 3000)
        throw xTooBig();
    if(size < 1)
        throw xNegative();
        
        pType = new int[size];
        for(int i = 0; i<size; i++)
            pType[i] = 0;
}

int main()
{
    
try
{
    Array intArray(0);
    for (int j = 0; j< 100; j++)
    {
        intArray[j] = j;
        std::cout<<"intArray[" <<j<< "j okay..."<<std::endl;
    }
}

catch(Array::xBoundary)
{
    std::cout <<"Unable to process the input!\n";
}

catch (Array::xTooBig)
{
    std::cout<<"This array is too big..."<<std::endl;
}

catch (Array::xTooSmall)
{
    std::cout<<"This array is too small..."<<std::endl;
}

catch(Array::xZero)
{
    std::cout<<"The programmer asked for an array of zero objects"<<std::endl;
}

catch (...)
{
    std::cout<<"Something went wrong, bit i've no idea what!"<<std::endl;
}

std::cout <<"Done\n";
}

[Ganado]

You nee to implement these member functions that you declared.

    int& operator[] (int offset);
    const int& operator[] (int offset) const;
    

https://www.geeksforgeeks.org/overloading-subscript-or-array-index-operator-in-c/