std::ranges::iota_view<W, Bound>:: size

Returns the size of the view if the view is bounded.

For the definitions of /*advanceable*/ and /*is-integer-like*/ , see advanceable and is-integer-like respectively.

Return value

If any of W and Bound is not a integer-like type , returns to-unsigned-like  ( bound_ - value_  ) .

Otherwise, returns ( value_ < 0 ) ?
(
( bound_ < 0 ) ?
to-unsigned-like  ( - value_  ) - to-unsigned-like  ( - bound_  ) :
to-unsigned-like  ( bound_  ) + to-unsigned-like  ( - value_  )
) :
to-unsigned-like  ( bound_  ) - to-unsigned-like  ( value_  ) .

Example

#include <cassert>
#include <ranges>
 
int main()
{
    unsigned initial_value{1}, bound{5};
    auto i{std::views::iota(initial_value, bound)};
    assert(i.size() == bound - initial_value and i.size() == 4);
 
    auto u{std::views::iota(8)};
    // assert(u.size()); // Error: size() is not present since “u” is unbounded
}

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

See also