Question

I’m developing a credential provider and credential. So I have this class SampleProvider and SampleCredential. It works well when I specifically declare that SampleProvider has one, or two, or a constant number of SampleCredential, by declaring:

SampleCredential * _pCredential[2]

But now, I want it to be dynamically allocated. So I will have this:

SampleCredential * *_pCredential

And then inside the method SetUsageScenario(), the code will read the number of credentials from a txt file, and allocate it:

(*_pCredential) = new SampleCredential[numberCount];

But it is not working. I keep getting error on that line. It says

Access violation writing location 0x00000000 ;

Do you know what happens here and what to do?

Answer 1

_pCredential has probably not been initialized yet and is still NULL. Attempting to dereference the null pointer via “(*_pCredential)” would then result in your access violation.

Maybe you meant to do this?

_pCredential = new SampleCredential*[numberCount];

That will allocate an array of pointers to SampleCredential objects. You can then allocate each SampleCredential object like this:

_pCredential[0] = new SampleCredential();
// etc.

Remember to free the memory when you’re done:

for (int i = 0; i < numberCount; i++) {
    delete _pCredential[i];
}
delete [] _pCredential;