std::ranges::split_view<V,Pattern>::begin
From cppreference.com
< cpp | ranges | split view
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.
Contents |
[edit] Parameters
(none)
[edit] Return value
An iterator.
[edit] Complexity
Amortized 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 or a sentinel to the end (public member function) | |
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) |