CODEWITHSUNDEEP
qtqpointer
Nyaruko
Nyaruko

Reputation: 4499

QPointer check is NULL?

When I delete the object the QPointer is pointing to, I check the value of the QPointer, and it is not NULL, but when I check its isNull function, it returns true.

And more strangely, when I do (!m_qpointer) it also returns true. So how is this possible?

Upvotes: 3

Views: 2374

Answers (1)

thuga
thuga

Reputation: 12931

(!m_qpointer) returns true when you delete the object it is pointing to, because of this operator defined in qpointer.h:

inline operator T*() const
    { return static_cast<T*>(const_cast<QObject*>(o)); }

It returns the pointer it is guarding. If it has been deleted, then it will be null.

isNull() returns true if the pointer it is guarding is null:

inline bool isNull() const
    { return !o; }

Now I'm not sure what do you mean by I check the value of the QPointer, and it is not NULL. Why should it be null? The QPointer object should still be a valid object even after deleting the pointer it is guarding.

Upvotes: 4

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