std::ranges:: views:: take_while, std::ranges:: take_while_view
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Defined in header
<ranges>
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||
|
template
<
ranges::
view
V,
class
Pred
>
requires
ranges::
input_range
<
V
>
&&
|
(1) | (since C++20) |
|
namespace
views
{
inline
constexpr
/*unspecified*/
take_while
=
/*unspecified*/
;
|
(2) | (since C++20) |
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Call signature
|
||
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template
<
ranges::
viewable_range
R,
class
Pred
>
requires
/* see below */
|
(since C++20) | |
|
template
<
class
Pred
>
constexpr /*range adaptor closure*/ take_while ( Pred && pred ) ; |
(since C++20) | |
view
of the elements from an underlying sequence, starting at the beginning and ending at the first element for which the predicate returns
false
.
take_while_view
models the concepts
contiguous_range
,
random_access_range
,
bidirectional_range
,
forward_range
, and
input_range
when the underlying view
V
models respective concepts.
Data members
| Member name | Definition |
base_
(private)
|
the underlying
view
of type
V
( exposition-only member object* ) |
pred_
(private)
|
the underlying function object of type
copyable-box
<Pred>
(until C++23)
movable-box
<Pred>
(since C++23)
( exposition-only member object* ) |
Member functions
constructs a
take_while_view
(public member function) |
|
|
returns a copy of the underlying (adapted) view
(public member function) |
|
|
returns a reference to the stored predicate
(public member function) |
|
|
returns an iterator to the beginning
(public member function) |
|
|
returns a sentinel representing the end
(public member function) |
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Inherited from std::ranges::view_interface |
|
returns whether the derived view is empty. Provided if it satisfies
sized_range
or
forward_range
.
(public member function of
std::ranges::view_interface<D>
)
|
|
|
(C++23)
|
returns a constant iterator to the beginning of the range.
(public member function of
std::ranges::view_interface<D>
)
|
|
(C++23)
|
returns a sentinel for the constant iterator of the range.
(public member function of
std::ranges::view_interface<D>
)
|
|
returns whether the derived view is not empty. Provided if
ranges::empty
is applicable to it.
(public member function of
std::ranges::view_interface<D>
)
|
|
gets the address of derived view's data. Provided if its iterator type satisfies
contiguous_iterator
.
(public member function of
std::ranges::view_interface<D>
)
|
|
returns the first element in the derived view. Provided if it satisfies
forward_range
.
(public member function of
std::ranges::view_interface<D>
)
|
|
returns the
n
th
element in the derived view. Provided if it satisfies
random_access_range
.
(public member function of
std::ranges::view_interface<D>
)
|
|
Deduction guides
Nested classes
|
the sentinel type
( exposition-only member class template* ) |
Example
#include <iostream> #include <ranges> int main() { for (int year : std::views::iota(2020) | std::views::take_while([](int y){ return y < 2026; })) std::cout << year << ' '; std::cout << '\n'; const char note[]{"Today is yesterday's tomorrow!..."}; auto not_dot = [](char c){ return c != '.'; }; for (char x : std::ranges::take_while_view(note, not_dot)) std::cout << x; std::cout << '\n'; }
Output:
2020 2021 2022 2023 2024 2025 Today is yesterday's tomorrow!
See also
|
(C++20)
|
a
view
consisting of the first N elements of another
view
(class template) (range adaptor object) |
a
view
consisting of the elements of another
view
, skipping the initial subsequence of elements until the first element where the predicate returns
false
(class template) (range adaptor object) |