Re: reinterpret_cast<int&<( int* ) -- Odd behavior
On 1 Kwi, 23:53, "Hak...@gmail.com" <Hak...@gmail.com> wrote:
The fallowing code produces output I would not expect:
#include <iostream>
using namespace std;
int main()
{
int x = 5;
int* y = &x;
int& z = reinterpret_cast<int&>( y );
cout << hex;
cout << &y << " 0x" << z << '\n';
}
When compiled with g++, the output shows that &y and z are the same.
What I might expect is z to be 5.
What you expected could be achived in a straight-forward way:
int& z = *y;
The real-world code that actually gave me a problem was trying to use C
++ and POSIX threads. I had a buffer type that I passed in as the
argument to my threadable function but I wanted to use it like a
reference. I quickly popped out this:
template< typename T >
void* f( void* _buf )
{
Buf<T>& buf = reinterpret_cast<Buf<T>&>( _buf );
....
}
If _buf is a pointer to Buf<T> object then the proper
code could look like this:
Buf<T>& buf = *static_cast<Buf<T>*>(_buf);
I think that this behavior of reinterpret_cast is supposed
to ensure that:
static_cast<T&>(obj) == reinterpret_cast<T&>(obj)
wich is rather intuitive when static_cast is applicable.
Cheers
Sfider
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