if (x->isNull()) crashes if x is not initialized

[sedi]

Hi,
I wanted to use (x->isNull()) to find out, if I can safely use a pointer to something. However, if I use it like this:

SomeType *x;
//doing some work, perhaps giving x a new object to point to, perhaps not
if (x->isNull()) return false;

SomeType *x;
//doing some work, perhaps giving x a new object to point to, perhaps not
if (x->isNull()) return false;

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the program crashes on the if-condition. I can see why: there is no object to get the ->isNull() method from.

If I use:

if (x==0) return false;

if (x==0) return false;

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instead, it works.

Now I have three curious questions:

1. Is it "legal" (aka: advisable) to use the second approach?
2. Will *-Declarations ensure that the Variable points to 0 before it gets an object to point to?
3. Is there any use for ->isNull()?