std::ranges::split_view<V,Pattern>::begin

 

C++

Compiler support

Freestanding and hosted

Language

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Concurrency support library (C++11)

Technical specifications

Symbols index

External libraries

 

Ranges library

Range access
begin cbegin end cend	rbegin crbegin rend crend	size ssize data cdata	empty
Range conversions
to (C++23)
Range primitives
range_size_trange_difference_t range_value_t	range_reference_trange_const_reference_trange_rvalue_reference_t   (C++23)	iterator_tconst_iterator_tsentinel_t (C++23)
Dangling iterator handling
dangling	borrowed_iterator_t	borrowed_subrange_t
Range concepts
range borrowed_range    sized_range constant_range (C++23)	common_range view viewable_range	input_range output_range forward_range	bidirectional_range random_access_range contiguous_range
Views
view_interface	subrange
Factories
empty_viewviews::empty iota_viewviews::iota	single_viewviews::single basic_istream_viewviews::istream	repeat_viewviews::repeat (C++23)(C++23)
Adaptors
ref_view views::all_tviews::all common_viewviews::common owning_view views::counted reverse_viewviews::reverse zip_viewviews::zip (C++23)(C++23) as_const_viewviews::as_const (C++23)(C++23) as_rvalue_viewviews::as_rvalue (C++23)(C++23)	take_viewviews::take take_while_viewviews::take_while drop_viewviews::drop drop_while_viewviews::drop_while zip_transform_viewviews::zip_transform (C++23)(C++23) adjacent_transform_viewviews::adjacent_transform (C++23)(C++23)   cartesian_product_viewviews::cartesian_product (C++23)(C++23)	elements_viewviews::elements keys_viewviews::keys values_viewviews::values transform_viewviews::transform adjacent_viewviews::adjacent (C++23)(C++23) slide_viewviews::slide (C++23)(C++23) stride_viewviews::stride (C++23)(C++23)	filter_viewviews::filter join_viewviews::join split_viewviews::split lazy_split_viewviews::lazy_split join_with_viewviews::join_with (C++23)(C++23) chunk_viewviews::chunk (C++23)(C++23) chunk_by_viewviews::chunk_by (C++23)(C++23)
Range adaptor objects
Range adaptor closure objects
Helper items
copyable-box	simple-view

 

std::ranges::split_view

Member functions

split_view::split_view (C++20)

split_view::base (C++20)

split_view::begin (C++20)

split_view::end (C++20)

Nested classes

split_view::iterator (C++20)

split_view::sentinel (C++20)

Deduction guides

 

constexpr /*iterator*/ begin();		(since C++20)

Returns an iterator to the first found subrange.

In order to provide the amortized constant time complexity required by the range concept, this function caches the result within the split_view for use on subsequent calls. Equivalent to

constexpr /*iterator*/ begin() {
  if (!cached_begin_.has_value())
    cached_begin_ = this->find_next(ranges::begin(base_));
  return { *this, ranges::begin(base_), cached_begin_.value() };
}

Exposition only data members base_ and cached_begin_ are described here.

Parameters

(none)

Return value

An iterator.

Complexity

Amortized \(\scriptsize \mathcal{O}(1)\)O(1).

Example

A link to check the code: wandbox

Run this code

#include <iostream>
#include <iomanip>
#include <ranges>
#include <string_view>
 
int main()
{
    constexpr std::string_view sentence{ "Keep..moving..forward.." };
    constexpr std::string_view delim{ ".." };
    std::ranges::split_view words{ sentence, delim };
 
    std::cout << "begin(): " << std::quoted( std::string_view{*words.begin()} )
              << "\nSubstrings: ";
    for (std::string_view word: words)
        std::cout << std::quoted(word) << ' ';
 
    std::ranges::split_view letters{ sentence, std::string_view{""} };
    std::cout << "\nbegin(): " << std::quoted( std::string_view{*letters.begin()} )
              << "\nLetters: ";
    for (std::string_view letter: letters)
        std::cout << std::quoted(letter, '\'') << ' ';
}

Output:

begin(): "Keep"
Substrings: "Keep" "moving" "forward" "" 
begin(): "K"
Letters: 'K' 'e' 'e' 'p' '.' '.' 'm' 'o' 'v' 'i' 'n' 'g' '.' '.' 'f' 'o' 'r' 'w' 'a' 'r' 'd' '.' '.'

See also

end (C++20)	returns an iterator or a sentinel to the end (public member function)
begin (C++20)	returns an iterator to the beginning (public member function of std::ranges::lazy_split_view<V,Pattern>)
ranges::begin (C++20)	returns an iterator to the beginning of a range (customization point object)