CODEWITHSUNDEEP
c++pointersmemory-managementshared-memory
user3085931
user3085931

Reputation: 1803

How to save a pointer address, so that another pointer can continue working on it?

Is there a way to store the address of a pointer into an arbitrary variable (e.g. an int) and to use this variable again to assign the address of a second pointer?

I know you can easily do

int* p1;
int* p2;
p2 = p1;

What I'm looking for is something like this

int* p1;
int* p2;
long addr_p1 = (long)p1;
p2 = doMagicCast(addr_p1);

Thanks for any advise

Upvotes: 1

Views: 110

Answers (1)

Jabberwocky
Jabberwocky

Reputation: 50775

This is the correct C++ way:

#include <cinttypes>

int main() {
  int* p1;
  int* p2;
  std::uintptr_t addr_p1 = reinterpret_cast<std::uintptr_t>(p1);
  p2 = reinterpret_cast<int*>(addr_p1);
}

You need to use std::uintptr_t instead of long because there is no guarantee that a long can hold a pointer.

But on 32 bit platform (where long and pointers usually have 32 bits) your initial approach using long may work.

Upvotes: 3

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