Container of iterators (newbie)

[Carter]

Hi,

I am trying to construct a container of iterators using STL and I seem
to be getting an error which I have been having difficulties figuring
out. The code is as follows:

std::list< std::list<K>::iterator > _scopes;

Which gives the following error:

type/value mismatch at argument 1 in template parameter list for
‘template<class _Tp, class _Alloc> class std::list’
environment.cpp:46: error: expected a type, got
‘std::list::iterator’
environment.cpp:46: error: template argument 2 is invalid

If anyone can shed light on this I would appreciate it.

Thanks in advance,

 

[Kai-Uwe Bux]

Hi,

I am trying to construct a container of iterators using STL and I seem
to be getting an error which I have been having difficulties figuring
out. The code is as follows:

std::list< std::list<K>::iterator > _scopes;

Which gives the following error:

type/value mismatch at argument 1 in template parameter list for
?template<class _Tp, class _Alloc> class std::list?
environment.cpp:46: error: expected a type, got
?std::list::iterator?
environment.cpp:46: error: template argument 2 is invalid

Presumably, the above line is part of a template and K is a typename
parameter to that template. Then, you should try:

std::list< typename std::list<K>::iterator > _scopes;


Best

Kai-Uwe Bux

 

[Carter]

Presumably, the above line is part of a template and K is a typename
parameter to that template. Then, you should try:

  std::list< typename std::list<K>::iterator > _scopes;

Best

Kai-Uwe Bux

Thanks that fixed the problem. I am however curious as to when in
general the addition of typename is required to disambiguate things
for the compiler. What exactly and when should you add the additional
typename keyword to a declaration?

Thanks,

Carter