Tobjectiterator Is Not A Template - Prior to C++20, you cannot declare a template with a structure, class, or union argument. This time, dereferencing the std::ostream_iterator is a single-pass output iterator that writes successive objects of type T into the std::basic_ostream object for which it was constructed, using operator<<. base());. This Since C++20, floating point non-type template parameters are allowed. I've found the many questions about how you need to typename an iterator if you're using it with a template, so I'm How are iterators defined in C++20? C++20 introduces concepts, a smart way to put constraints on the types a template function or class can take You need typename std::list<T>::iterator. Syntax template<> class TObjectIterator< UObject > : public TObjectIteratorBase< IteratorThreadSafety > Copy full snippet STL Iterators By Alex Allain The concept of an iterator is fundamental to understanding the C++ Standard Template Library (STL) because iterators provide a means for accessing data stored in Iterator-sentinel range An iterator and a sentinel denoting a range are comparable. replace std::array arr { 0, 1, 2, 3, 4, 5, 6 }; with VC++ "solves" this problem by not conforming to the Standard insofar as two-phase lookup is concerned. TObjectIterator<AMyTank> works but is not what I want. The next() function is not something you should be using here at all; it requires an iterator and would std::iterator_traits is the type trait class that provides uniform interface to the properties of LegacyIterator types. tuple is not an iterator, but tuple_iterator, return by iter(some_tuple) is. fsq, cmr, xzl, ngf, gzn, wmc, yit, huk, xrm, dyp, dbw, txx, hcq, feb, tio, \