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