std::includes

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Defined in header <algorithm>

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template< class InputIterator1, class InputIterator2 >

bool includes( InputIterator1 first1, InputIterator1 last1,

               InputIterator2 first2, InputIterator2 last2 );

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template< class InputIterator1, class InputIterator2 >

bool includes( InputIterator1 first1, InputIterator1 last1,

               InputIterator2 first2, InputIterator2 last2, Compare comp );

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Returns true if every element from the sorted range [first2, last2) is found within the sorted range [first, last). Also returns true if [first2, last2) is empty.

The first version expects both ranges to be sorted with operator<, the second version expects them to be sorted with the given comparison function comp.

Parameters

first1, last1	-	the sorted range of elements to examine
first2, last2	-	the sorted range of elements to search for
comp	-	comparison function object (i.e. an object that satisfies the requirements of Compare) which returns true if the first argument is less than the second. The signature of the comparison function should be equivalent to the following: bool cmp(const Type1& a, const Type2& b); While the signature does not need to have const&, the function must not modify the objects passed to it and must be able to accept all values of type (possibly const) Type1 and Type2 regardless of value category (thus, Type1& is not allowed, nor is Type1 unless for Type1 a move is equivalent to a copy(since C++11)). The types Type1 and Type2 must be such that an object of type InputIterator can be dereferenced and then implicitly converted to both of them.

Return value

true if every element from [first2, last2) is a member of [first, last).

Complexity

At most 2·(N₁+N₂-1) comparisons, where N₁ = std::distance(first1, last1) and N₂ = std::distance(first2, last2).

Example

Run this code

#include <iostream>
#include <algorithm>
#include <cctype>
 
int main()
{
  std::vector<char> v1 {'a', 'b', 'c', 'f', 'h', 'x'};
  std::vector<char> v2 {'a', 'b', 'c'};
  std::vector<char> v3 {'a', 'c'};
  std::vector<char> v4 {'g'};
  std::vector<char> v5 {'a', 'c', 'g'};
  std::vector<char> v6;
 
  for (auto i : v1) std::cout << i << ' ';
  std::cout << "includes:\n";
 
  for (auto i : v2) std::cout << i << ' ';
  std::cout << ": " << std::includes(v1.begin(), v1.end(), v2.begin(), v2.end()) << '\n';
  for (auto i : v3) std::cout << i << ' ';
  std::cout << ": " << std::includes(v1.begin(), v1.end(), v3.begin(), v3.end()) << '\n';
  for (auto i : v4) std::cout << i << ' ';
  std::cout << ": " << std::includes(v1.begin(), v1.end(), v4.begin(), v4.end()) << '\n';
  for (auto i : v5) std::cout << i << ' ';
  std::cout << ": " << std::includes(v1.begin(), v1.end(), v5.begin(), v5.end()) << '\n';
  for (auto i : v6) std::cout << i << ' ';
  std::cout << ": " << std::includes(v1.begin(), v1.end(), v6.begin(), v6.end()) << '\n';
 
  auto cmp_nocase = [](char a, char b) {
    return std::tolower(a) < std::tolower(b);
  }
  std::vector<char> v7 {'A', 'B', 'C'};
  for (auto i : v7) std::cout << i << ' ';
  std::cout << ": "
            << std::includes(v1.begin(), v1.end(), v7.begin(), v7.end(), cmp_nocase)
            << '\n';
}

Output:

a b c f h x includes:
a b c : 1
a c : 1
g : 0
a c g : 0
A B C : 1

See also

Template:cpp/algorithm/dcl list set differenceTemplate:cpp/algorithm/dcl list search