Re: pointer to pointer
On Feb 26, 10:19 pm, cbarr...@ix.netcom.com (Carl Barron) wrote:
Mitesh <oopsbab...@hotmail.com> wrote:
A pointer to a pointer might be used when ever another level of
indirection simplifies the problem.
remember also
double *a = ...;
double *b = ...;
tyoedef double *Ptr;
you mean 'typedef' :)
Ptr & c = a;
Ptr * d = a;
You left off an ampersand
Ptr * d = &a;
c = b // modifies a (a = b)
d = b // does not modify a
Nor does it even compile. 'd' is a pointer to a pointer. 'b' is a
pointer. The later can not be assigned to the former.
Pointer-to-pointer is just as useful as reference-to-pointer, except
pointer-to-pointer can be null, while reference-to-pointer can not be
null.
As others have pointed out, a common use case is an object factory:
void create(T** pp) {
if (pp) *pp = new T();
}
void create(T*& rp) {
rp = new T();
}
joshua lehrer
http://www.lehrerfamily.com/
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