std::ranges::includes
Defined in header <algorithm>
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Call signature |
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template< std::input_iterator I1, std::sentinel_for<I1> S1, std::input_iterator I2, std::sentinel_for<I2> S2, |
(1) | (since C++20) |
template< ranges::input_range R1, ranges::input_range R2, class Proj1 = std::identity, class Proj2 = std::identity, |
(2) | (since C++20) |
[
first2,
last2)
is a subsequence of the projections of the sorted range [
first1,
last1)
.Both ranges must be sorted with the given comparison function comp. A subsequence need not be contiguous.
The function-like entities described on this page are niebloids, that is:
- Explicit template argument lists cannot be specified when calling any of them.
- None of them are visible to argument-dependent lookup.
- When any of them are found by normal unqualified lookup as the name to the left of the function-call operator, argument-dependent lookup is inhibited.
In practice, they may be implemented as function objects, or with special compiler extensions.
Contents |
Parameters
first1, last1 | - | the sorted range of elements to examine |
r1 | - | the sorted range of elements to examine |
first2, last2 | - | the sorted range of elements to search for |
r2 | - | the sorted range of elements to search for |
comp | - | comparison function to apply to the projected elements |
proj1 | - | projection to apply to the elements in the first range |
proj2 | - | projection to apply to the elements in the second range |
Return value
true if [
first2,
last2)
is a subsequence of [
first1,
last1)
; otherwise false.
Complexity
At most 2·(N1+N2-1) comparisons, where N1 is ranges::distance(r1) and N2 is ranges::distance(r2).
Possible implementation
This section is incomplete Reason: no eq fun |
Example
#include <algorithm> #include <cctype> #include <initializer_list> #include <iomanip> #include <iostream> #include <locale> #include <string> template<class T> std::ostream& operator<<(std::ostream& os, std::initializer_list<T> const& list) { for (os << "{ "; auto const& elem : list) os << elem << ' '; return os << "} "; } struct true_false : std::numpunct<char> { std::string do_truename() const { return "? Yes\n"; } std::string do_falsename() const { return "? No\n"; } }; int main() { std::cout.imbue(std::locale(std::cout.getloc(), new true_false)); auto ignore_case = [](char a, char b) { return std::tolower(a) < std::tolower(b); }; const auto a = {'a', 'b', 'c'}, b = {'a', 'c'}, c = {'a', 'a', 'b'}, d = {'g'}, e = {'a', 'c', 'g'}, f = {'A', 'B', 'C'}, z = {'a', 'b', 'c', 'f', 'h', 'x'}; std::cout << z << "includes\n" << std::boolalpha << a << std::ranges::includes(z.begin(), z.end(), a.begin(), a.end()) << b << std::ranges::includes(z, b) << c << std::ranges::includes(z, c) << d << std::ranges::includes(z, d) << e << std::ranges::includes(z, e) << f << std::ranges::includes(z, f, ignore_case); }
Output:
{ a b c f h x } includes { a b c } ? Yes { a c } ? Yes { a a b } ? No { g } ? No { a c g } ? No { A B C } ? Yes
See also
(C++20) |
computes the difference between two sets (niebloid) |
(C++20) |
searches for the first occurrence of a range of elements (niebloid) |
(C++23)(C++23) |
checks if the range contains the given element or subrange (niebloid) |
returns true if one sequence is a subsequence of another (function template) |