You need to instantiate an object in order to call its member functions. The member functions need an object to operate on; they can't just be used on their own. The main()
function could, for example, look like this:
int main()
{
Name_pairs np;
cout << "Enter names and ages. Use 0 to cancel.\n";
while(np.test())
{
np.read_names();
np.read_ages();
}
np.print();
keep_window_open();
}