In an algorithm, I can determine the value_type directly from the iterator via iter::value_type. Why do algorithms use iterator_traits to do the same? #include <iostream> #include <v...

I have a trouble with using std::views::filter on joined streams/ranges. I don't know what's exactly wrong here. I suppose the elements may not be passed with the proper (copy/move) semantics, refe...

C++20 brings a more powerful iterator system, one of them is to introduce iterator_concept on the basis of iterator_category. I found that the iterator_concept and iterator_category of many iterato...

I'm doing this: const int arr[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 }; const auto foo = cbegin(arr); const typename iterator_traits<decltype(foo)>::value_type bar = 1; I would ha...

I see that iterator_traits always defines a difference_type: https://en.cppreference.com/w/cpp/iterator/iterator_traits#Member_types I'm just wondering why, wouldn't that be ptrdiff_t for every ty...

C++17 introduced the concept of ContiguousIterator http://en.cppreference.com/w/cpp/iterator. However it doesn't seem that there are plans to have a contiguous_iterator_tag (in the same way we now ...

It appears that the iterator adaptor reverse_iterator doubly defines most of its nested types. In particular, it inherits publicly from std::iterator which exposes iterator_category, value_type, di...

I'd like to specialize std::iterator_traits<> for iterators of a container class template that does not have the usual nested typedefs (like value_type, difference_type, etc.) and whose sourc...

In my project, I want to split stream into some given type of values, so I implement a template function as template <typename TElem, typename TOutputIter> TOutputIter SplitSpace(std::istrea...

How does one define forward-output-iterators in C++11 in a canonical way? According to the standard a forward_iterator is only a input_iterator. So the corresponding forward_iterator_tag only exte...

Are ForwardIterators required to be OutputIterators? My current STL-implementation (VS2012) derives forward_iterator_tag from both input_iterator_tag and output_iterator_tag, but I can't find this ...

In the C++ standard library, why is std::iterator_traits<const T*>::value_type the same type as std::iterator_traits<T*>::value_type Why it is designed like that? Shouldn't the first ...

I am new to C++ so please bear with me. I am trying to understand STL iterator_traits. In the book "The C++ Standard Library" the structure iterator_traits is defined as follows: template...

I have the following code: template<typename T, typename Allocator = std::allocator<T> > class Carray { // ... typedef T* pointer; typedef pointer iterator; // ... }; Now I'm try...