Factory design

#include <iostream>
using namespace std;

class Invoice
{
public:
    virtual void printInvoice() = 0;
};

class clsInvoiceWithHeader : public Invoice
{
public:
    void printInvoice()
    {
        cout << "Hello Client -  I am clsInvoiceWithHeader" << endl;
    }
};
class clsInvoiceWithoutHeader : public Invoice
{
public:
    void printInvoice()
    {
        cout << "Hello Client -  I am clsInvoiceWithoutHeader" << endl;
    }
};

class FactoryInvoice
{
public:
    static Invoice * getInvoiceType( int inttype) ;
};
//static Invoice * invoice = nullptr;



Invoice * FactoryInvoice::getInvoiceType( int inttype)
{
        Invoice * i = nullptr;
        if( inttype == 1)
        {
            return (new clsInvoiceWithHeader());
        }
        if ( inttype == 2)
        {
            return (new clsInvoiceWithoutHeader());
        }
        else
            return nullptr;
}

int main()
{
    Invoice* iv = FactoryInvoice::getInvoiceType(1);
    iv -> printInvoice();
    return 0;
}