Remove Function 使程序崩溃 C++

Question

/********************************************
*   Remove the last employee from the list  *
********************************************/
void EmployeeList::Remove() 
{
    newEmployee * nextToEnd = head, 
                * last = head->Next();

    //THIS IS THE PROBLEM
    //no nodes
    if(head == NULL)
        return;

    //remove the only employee in the list
    if(head->Next()== NULL)
    {
        cout << "\n\t\tEmployee ID " << head->empID() << " and salary $" 
             << head->ySalary() << " have been removed.\n"; 
        head = NULL;
        delete head;
    }

    else
    {  
       // remove the last employee of the list
        while(last->Next() != NULL)
        {
            nextToEnd = last;
            last = last->Next();
        }   

       cout << "\n\t\tEmployee ID " << last->empID() << " and salary $" 
            << last->ySalary() << " have been removed.\n";  

        delete last;
        nextToEnd->SetNext(NULL);      
    }
}

having problem when trying to remove from an empty list. I know i cant remove if it is empty but i would instead of crashing the program to display "The Employee List is empty.

I specified where I think the problem hoping someone can help me out to figure it out.

Answer 1

All you have to do is what's already shown in the code. Notice how it outputs text to console using cout . Change the if statement where you specified the 'problem' is to output a message and then return.

But your program crashing has nothing to do with what you have marked. It is crashing because of head->Next() . You can't call a method on an object that is NULL . That should be occurring after the if (head == NULL) check.