# std::ranges::take_while_view<V,Pred>::begin

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< cpp‎ | ranges‎ | take while view

constexpr auto begin() requires (!__SimpleView<V>); | (1) | (since C++20)
constexpr auto begin() const requires ranges::range<const V> && std::indirect_unary_predicate<const Pred, ranges::iterator_t<const V>>; | (2) | (since C++20)

Returns an iterator to the first element of the view. Effectively calls ranges::begin on the underlying view.

Overload (1) does not participate in overload resolution if `V` is a simple view (that is, if `V` and const V are views with the same iterator and sentinel types).

### Parameters

(none)

### Return value

ranges::begin(base_), where `base_` is the underlying view.

### Example

| This section is incomplete Reason: no example

### Defect reports

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

DR | Applied to | Behavior as published | Correct behavior
--- | --- | --- | ---
LWG 3450 | C++20 | the const overload might return an iterator non-comparable to the sentinel | constrained

### See also

end (C++20) | returns a sentinel representing the end (public member function)
operator== (C++20) | compares a sentinel with an iterator returned from `take_while_view::begin` (function)

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