std::experimental::ranges::for_each

 

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Technical specifications

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Algorithms library

Non-modifying sequence operations
all_ofany_ofnone_of countcount_if	findfind_iffind_if_not find_end find_first_of	adjacent_find search search_n mismatch	equal for_each lexicographical_compare
Modifying sequence operations
copycopy_if copy_n copy_backward move move_backward	fill fill_n generate generate_n swap_ranges shuffle transform	removeremove_if replacereplace_if reverse rotate unique	remove_copyremove_copy_if replace_copyreplace_copy_if reverse_copy rotate_copy unique_copy
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is_partitioned partition_point	partition partition_copy	stable_partition
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is_sorted is_sorted_until	sort stable_sort	partial_sort partial_sort_copy	nth_element
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lower_bound	upper_bound	binary_search	equal_range
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merge inplace_merge	includes	set_difference set_intersection	set_symmetric_difference set_union
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is_heap is_heap_until	make_heap sort_heap	push_heap pop_heap
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max max_element	min min_element	minmax minmax_element
Permutations
is_permutation	next_permutation	prev_permutation

 

Defined in header <experimental/ranges/algorithm>
template< InputIterator I, Sentinel<I> S, class Proj = ranges::identity,           IndirectUnaryInvocable<projected<I, Proj>> Fun > ranges::tagged_pair<tag::in(I), tag::fun(Fun)>     for_each( I first, S last, Fun f, Proj proj = Proj{} );	(1)	(ranges TS)
template< InputRange R, class Proj = ranges::identity,           IndirectUnaryInvocable<projected<ranges::iterator_t<R>, Proj>> Fun > ranges::tagged_pair<tag::in(ranges::safe_iterator_t<R>), tag::fun(Fun)>     for_each( R&& r, Fun f, Proj proj = Proj{} );	(2)	(ranges TS)

1) Invokes the given function object f to the result of invoking the projection proj on dereferencing every iterator in the range [first, last) (i.e.,ranges::invoke(f, ranges::invoke(proj, *i))), in order.

2) Same as (1), but uses r as the source range, as if using ranges::begin(r) as first and ranges::end(r) as last.

For both overloads, if the iterator type is mutable, f may modify the elements of the range through the dereferenced iterator. If f returns a result, the result is ignored.

Unlike the rest of the algorithms, for_each is not allowed to make copies of the elements in the sequence even if they are trivially copyable.

Unlike std::for_each (which requires only MoveConstructible), these functions require Fun to model CopyConstructible.

Notwithstanding the declarations depicted above, the actual number and order of template parameters for algorithm declarations is unspecified. Thus, if explicit template arguments are used when calling an algorithm, the program is probably non-portable.

Parameters

first, last	-	the range to apply the function to
r	-	the range to apply the function to
f	-	callable object to be applied to each projected element in the range
proj	-	projection to apply to the elements

Return value

A tagged_pair object containing the following two members:

• The first member, with the tag tag::in, is the past-the-end iterator of the source range (that is, an iterator of type I that compares equal to the sentinel last).
• The second member, with the tag tag::fun, is initialized from std::move(f) (after all applications of the function object).

Complexity

Exactly last - first applications of f and proj.

Possible implementation

template<InputIterator I, Sentinel<I> S, class Proj = ranges::identity, IndirectUnaryInvocable<ranges::projected<I, Proj>> Fun> auto for_each(I first, S last, Fun f, Proj proj = Proj{}) -> ranges::tagged_pair<tag::in(I), tag::fun(Fun)> { for (; first != last; ++first) ranges::invoke(f, ranges::invoke(proj, *first)); return {std::move(first), std::move(f)}; }

See also

transform	applies a function to a range of elements (function template)
range-for loop(C++11)	executes loop over range
for_each	applies a function to a range of elements (function template)
for_each_n (C++17)	applies a function object to the first n elements of a sequence (function template)