function
<memory>
std::declare_no_pointers
void declare_no_pointers (char* p, size_t n);
Declare memory block as containing no pointers
Declares the range of memory starting at p and spanning n bytes as containing no traceable pointer locations.
This formally invalidates any object created with ::operator new whose address in only stored in that range. Notice though that compilers implementing a relaxed pointer safety policy may ignore this.
In garbage-collected implementations, a call to this function can cause objects whose only safely-derived pointer (or its integer representation) resides in the memory range to be collected.
undeclare_no_pointers must be called on the same range before the destruction of the object containing the range. The call to undeclare_no_pointers unregisters the range without restoring any validity to any dynamic object previously invalidated by the call to declare_no_pointers.
Parameters
- p
- Pointer to the first byte of the range to be declared.
No bytes of the specified range shall have been registered by a previous this function and not released.
- n
- The length, expressed in bytes, of the range to be declared.
size_t is an unsigned integral type.
Return value
none
This function throws no exceptions.
Example
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// declare_no_pointers / undeclare_no_pointers
#include <iostream>
#include <memory>
int main() {
int * foo = new int(1);
int * bar = new int(2);
std::declare_no_pointers (reinterpret_cast<char*>(&bar),sizeof(int*));
std::cout << "*foo: " << *foo << '\n';
if (std::get_pointer_safety() != std::pointer_safety::strict)
std::cout << "*bar: " << *bar << '\n'; // invalid if strict safety
std::undeclare_no_pointers (reinterpret_cast<char*>(&bar),sizeof(int*));
delete bar;
delete foo;
return 0;
}
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Possible output: