Finding the type of a pointed to element

[Adam H. Peterson]

I have a type T (in a template) which I know (or assume) is a pointer to
a pair type. I would like to find out what the type of the second
element in the pair is. If T were simply a pair, I could get this by
doing something like:

typedef typename T::second_type U;

But how do I handle when T is a _pointer_to_ a pair type (or actually an
iterator type for a pointer to some pair type)?

Thanks in advance,
Adam Peterson

 

[David Harmon]

On Tue, 06 Apr 2004 15:53:02 -0600 in comp.lang.c++, "Adam H. Peterson"

I have a type T (in a template) which I know (or assume) is a pointer to
a pair type. I would like to find out what the type of the second
element in the pair is. If T were simply a pair, I could get this by
doing something like:

typedef typename T::second_type U;

If your compiler has good support for template partial specialization I
think you should be able to use

typedef typename std::iterator_traits<T>::value_type::second_type U;

 

[Adam H. Peterson]

On Tue, 06 Apr 2004 15:53:02 -0600 in comp.lang.c++, "Adam H. Peterson"



If your compiler has good support for template partial specialization I
think you should be able to use

typedef typename std::iterator_traits<T>::value_type::second_type U;

g++ 3.2.2 20030222

Bravo. Thanks, it appears to work.

Adam