Cast pointer address to int

Question

Beginner question: How can I take the adress of a pointer and save it as an int? Example:

int *ptr = xyz;
int i = static_cast<int>(ptr);

So if ptr points to the memory adress 123, i should be 123. My compiler says it's an error: invalid static_cast from type 'int*' to type 'int'.

Guess I am missing something but I don't know what.

Why would you wanT to do this? – John Dibling Feb 01 '14 at 16:18 — John Dibling, Feb 01 '14 at 16:18
@JohnDibling interoperation with a poorly written C API? – user3175411 Feb 01 '14 at 16:28 — user3175411, Feb 01 '14 at 16:28

score 14 · Accepted Answer · answered Feb 01 '14 at 16:05

14

You can use reinterpret_cast. An int is not guaranteed to be able to losslessly store a pointer though, so you should use the std::intptr_t type instead.

answered Feb 01 '14 at 16:05

user3175411

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Okay thanks, ofcourse its reinterpret_cast... I tried dynamic_cast but totally forgot about reinterpret_cast. Sometimes I wake up and don't remember my name. Okay I made this one up but seriously, how could I forget that? ;) I know that pointers and ints can have different sizes but it does not matter for what I do. – chris342423 Feb 01 '14 at 16:09
@chris342423: if you are on a 64 bits machine, using `int` means you'll almost never see the real address. – Matthieu M. Feb 01 '14 at 18:02

score 2 · Answer 2 · edited May 23 '17 at 12:28

2

You can also use C-style casting:

int *ptr = xyz;
int i = (int) ptr;

Here's a nice discussion comparing C-style casting to reinterpret_cast.

edited May 23 '17 at 12:28

Community

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answered Feb 01 '14 at 16:13

1''

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score 0 · Answer 3 · answered Mar 29 '21 at 21:13

0

you can use the following function to get any pointer as unsigned long. int is not guaranteed to fulfill the task.

template <typename T>
static constexpr inline auto ptrToAddr(T *pointer) noexcept
{
  return reinterpret_cast<std::uintptr_t>(pointer);
}

answered Mar 29 '21 at 21:13

milad lashini

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Unsigned long isn’t guaranteed to work either. As the accepted answer says, this is what uintptr_t is for. – Sneftel Mar 29 '21 at 21:26
could you please tell me what is the type of uintptr_t on your machine? – milad lashini Mar 29 '21 at 21:34
It depends on the architecture. – Sneftel Mar 29 '21 at 21:38

Cast pointer address to int

3 Answers3