std::ranges::split_view<V,Pattern>::begin
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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 (by means of cached_begin_ member) for use on subsequent calls.
Let base_ be the underlying data member. 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()}; }
Contents
[edit] Return value
An iterator.
[edit] Complexity
Amortized \(\scriptsize \mathcal{O}(1)\)O(1).
[edit] Example
Run this code
#include <iomanip> #include <iostream> #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 (auto word : words) std::cout << std::quoted (std::string_view (word)) << ' '; std::ranges::split_view letters{sentence, std::string_view {""}}; std::cout << "\nbegin(): " << std::quoted (std::string_view {*letters.begin()}) << "\nLetters: "; for (auto letter : letters) std::cout << std::string_view (letter) << ' '; std::cout << '\n'; }
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 . .
[edit] See also
returns an iterator to the beginning
(public member function of
(public member function of
std::ranges::lazy_split_view<V,Pattern>) [edit]