operator-(ranges::transform_view::sentinel)
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                    < cpp | ranges | transform view | sentinel
                    
                                                            
                    |   friend constexpr ranges::range_difference_t<Base>     operator-( const /*iterator*/<Const>& x, const /*sentinel*/& y )  | 
(1) | (since C++20) | 
|   friend constexpr ranges::range_difference_t<Base>     operator-( const /*sentinel*/& y, const /*iterator*/<Const>& x )  | 
(2) | (since C++20) | 
Computes the distance between the underlying iterator of x and the underlying sentinel of y.
These functions are not visible to ordinary unqualified or qualified lookup, and can only be found by argument-dependent lookup when transform_view::sentinel<Const> is an associated class of the arguments.
Parameters
| x | - | an iterator | 
| y | - | a sentinel | 
Return value
Let current_ denote the underlying iterator, end_ denote the underlying sentinel.
1) x.current_ - y.end_
2) y.end_ - x.current_