std::ranges::split_view<V,Pattern>::begin
From cppreference.com
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()};
}
Return value
An iterator.
Complexity
Amortized O(1).
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 . .
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) |
