what is the meaning of & ?
if i have
int *p;
&p is the address of p
but is it just an argument
or we can get the value in p by
*(&p)
??
i thought &p return
is a string or a number which is the address of p (not type pointer)
so if i look at &p as a function then
it returns (non pointer value)
correct?
Bitwise and, or address-of operator.Originally Posted by transgalactic2
Yes, but that is more generally true: if p is of type T, then &p is of type pointer to T.
The result of &p is the address of p, which is a pointer.
The address-of operator is not a function, and again, its result is a pointer.
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so if i say *&p.value=7
its just like saying p->value=7
??
Yes. In fact, in C, neither of the operators * and & are evaluated in that case.
EDIT:
Oh sorry, your mistake, and now mine as well. *&p.value is equivalent to p.value. It is not equivalent to p->value.
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but p.value
has no meaning
we need *p.value to get the value
??
* and & when sticked together cancel each other
so whet i say *&p
or *&p
computer looks at them as p ??
??
In the context of the code presented in your first post, that is true.
If p.value has no meaning, then *p.value has no meaning, since it involves dereferencing the result of p.value.
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* and & when sticked together cancel each other
so whet i say *&p
or *&p
computer looks at them as p ??
??
I am not sure what you mean by "looks at them", but basically it treats *&p as if it were p.
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ok *& together cancel each other
then if you say that &p and p are the same thing
then why *&p and *p aren't the same thing
??
Where did I say that?
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&p and p are not the same thing. One is the address of p, the other is the value of p itself.
Hence, *&p means "pointer to address of p", which is the same as p, since pointer to uses the value as an address to get to the actual thing, and address of makes a pointer of to a variable.
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you said
"if p is of type T, then &p is of type pointer to T"
so &p is a pointer which holds the address of pointer p??
That's right. For example, if p is an int, then &p is an int*. If p is an int*, then &p is an int**.
&p is a pointer which holds the address of p.
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To clarify:
&p = the address of the p variable
*p = invalid, assuming that p is not a pointer. If p is a pointer, than dereferences the memory that p points to, e.g. reads the address of memory that p points to
*&p = a dereferencing of the address of the p variable, equates to p
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