Defined in header <ranges>
template< class T >
  concept common_range =
    ranges::range<T> && std::same_as<ranges::iterator_t<T>, ranges::sentinel_t<T>>;
(since C++20)

The common_range concept is a refinement of range for which std::ranges::begin() and std::ranges::end() return the same type (e.g. all standard library containers).


#include <ranges>
struct A {
    char* begin();
    char* end();
static_assert( std::ranges::common_range<A> );
struct B {
    char* begin();
    bool end();
};  // not a common_range: begin/end have different types
static_assert( not std::ranges::common_range<B> );
struct C {
    char* begin();
};  // not a common_range, not even a range: has no end()
static_assert( not std::ranges::common_range<C> );
int main() { }

© cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.