| Defined in header <algorithm> | ||
|---|---|---|
template< class InputIt1, class InputIt2 >
bool includes( InputIt1 first1, InputIt1 last1,
InputIt2 first2, InputIt2 last2 ); | (1) | |
template< class InputIt1, class InputIt2, class Compare >
bool includes( InputIt1 first1, InputIt1 last1,
InputIt2 first2, InputIt2 last2, Compare comp ); | (2) |
Returns true if every element from the sorted range [first2, last2) is found within the sorted range [first1, last1). 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 (i.e. is ordered before) the second. The signature of the comparison function should be equivalent to the following:
The signature does not need to have |
| Type requirements | ||
- InputIt must meet the requirements of InputIterator. | ||
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).
Possible implementation
| First version |
|---|
template<class InputIt1, class InputIt2>
bool includes(InputIt1 first1, InputIt1 last1,
InputIt2 first2, InputIt2 last2)
{
for (; first2 != last2; ++first1)
{
if (first1 == last1 || *first2 < *first1)
return false;
if ( !(*first1 < *first2) )
++first2;
}
return true;
} |
| Second version |
template<class InputIt1, class InputIt2>
bool includes(InputIt1 first1, InputIt1 last1,
InputIt2 first2, InputIt2 last2, Compare comp)
{
for (; first2 != last2; ++first1)
{
if (first1 == last1 || comp(*first2, *first1))
return false;
if (!comp(*first1, *first2))
++first2;
}
return true;
} |
Example
#include <iostream>
#include <algorithm>
#include <cctype>
#include <vector>
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'};
for (auto i : v1) std::cout << i << ' ';
std::cout << "\nincludes:\n" << std::boolalpha;
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';
auto cmp_nocase = [](char a, char b) {
return std::tolower(a) < std::tolower(b);
};
std::vector<char> v6 {'A', 'B', 'C'};
for (auto i : v6) std::cout << i << ' ';
std::cout << ": (case-insensitive) "
<< std::includes(v1.begin(), v1.end(), v6.begin(), v6.end(), cmp_nocase)
<< '\n';
}Output:
a b c f h x includes: a b c : true a c : true g : false a c g : false A B C : (case-insensitive) true
See also
| computes the difference between two sets (function template) | |
| searches for a range of elements (function template) | |
| std::experimental::parallel::includes
(parallelism TS) | parallelized version of std::includes (function template) |
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