Question

For a class assignment I need to implement a destructor for the objects of linked-list I’ve created. I made a function called MakeEmpty that I called inside the destructor. It compiled correctly the first time, but now I am getting instant crashes with an error saying:

Expression: _BLOCK_TYPE_IS_VALID(pHead->nBlockUse)

Can someone help me figure out what is wrong? I ran the debugger and pointed out where it says the error is in the code.

WORD::~WORD()
{
cout << "Destructor Called"<<endl;

(*this).MakeEmpty();
}

And this is the MakeEmpty() function

void WORD::MakeEmpty()
{
alpha_numeric *p = (*this).front;

if((*this).IsEmpty())
{
    cout <<"Already empty"<< endl;
    return;
}

while(front != 0)
{
    front = front -> next;
    delete p;//<<<<---DEBUGGER SAYS ERROR HERE
    p = front;
}
return;
}

Answer 1

You have a coding error… you need to: Bench check your code!

Write down the expected values of all variables at each statement and through each iteration of the loop. Don’t skip any steps. This will make your coding error obvious.

After 30 years I do this in my head.. but I always do it to make sure what I’ve written is correct. This one habit will serve you well in years to come.