std::output_iterator(3)

NAME
std::output_iterator - std::output_iterator

Synopsis
   Defined in header <iterator>
   template <class I, class T>
   concept output_iterator =
   std::input_or_output_iterator<I> &&
   std::indirectly_writable<I, T> && (since C++20)
   requires(I i, T&& t) {
   *i++ = std::forward<T>(t); // not required to be equality-preserving
   };
   The output_iterator concept is a refinement of input_or_output_iterator, adding the
   requirement that it can be used to write values of type and value category encoded
   by T (via indirectly_writable). equality_comparable is not required.
  Semantic requirements
   Let E be an expression such that decltype((E)) is T, and i be a dereferenceable
   object of type I. output_iterator<I, T> is modeled only if all the concepts it
   subsumes are modeled, and *i++ = E; has effects equivalent to *i = E; ++i;.
  Equality preservation
   An expression is equality preserving if it results in equal outputs given equal
   inputs.
     * The inputs to an expression consist of its operands.
     * The outputs of an expression consist of its result and all operands modified by
       the expression (if any).
   In specification of standard concepts, operands are defined as the largest
   subexpressions that include only:
     * an id-expression, and
     * invocations of std::move, std::forward, and std::declval.
   The cv-qualification and value category of each operand is determined by assuming
   that each template type parameter denotes a cv-unqualified complete non-array object
   type.
   Every expression required to be equality preserving is further required to be
   stable: two evaluations of such an expression with the same input objects must have
   equal outputs absent any explicit intervening modification of those input objects.

Notes
   Unlike the LegacyOutputIterator requirements, the output_iterator concept does not
   require that the iterator category tag be defined.
   Algorithms on output iterators should be single pass.

See also
   input_or_output_iterator specifies that objects of a type can be incremented and
   (C++20) dereferenced
                        (concept)