CODEWITHSUNDEEP
c++pointers
Stephen K
Stephen K

Reputation: 737

Multiple pointers to pointers

Looking through a projects code I found this:

font.Draw(x, y + 15 * 1, fontColor, "agPtr: %p <= %p", *(void**)agLocked.m_ptr, (void**)agLocked.m_ptr);

How is *(void**)agLocked.m_ptr

Different than (void**)agLocked.m_ptr?

Also this:

unsigned long shift = *(unsigned long*)all.m_ptr;
    shift = *(unsigned long*)(shift + 0x30);
    shift = *(unsigned long*)(shift + 0x28);
    shift = *(unsigned long*)(shift + 0x178);

I have looked at pointer arithmetic and all that and it doesn't make sense to me. Can someone point (heh) me in the right direction? is the first *(void**) accessing three pointers? why not use (void***)? While I am comfortable with c++ I would like to better understand the above so that I can contribute to the project.

Upvotes: 1

Views: 82

Answers (1)

David Schwartz
David Schwartz

Reputation: 182761

*(void**)agLocked.m_ptr

This dereferences agLocked.m_ptr to get a void * and will probably fault if it's NULL or contains junk.

(void**)agLocked.m_ptr

This just casts agLocks.m_ptr to a void **.

Upvotes: 2

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