Difference between revisions of "cpp/algorithm/includes"
m (Text replace - "{{eq fun cpp" to "{{eq fun") |
m (Text replace - "putIterator" to "putIt") |
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{{ddcl list header | algorithm}} | {{ddcl list header | algorithm}} | ||
{{ddcl list item | num=1 | | {{ddcl list item | num=1 | | ||
| − | template< class | + | template< class InputIt1, class InputIt2 > |
| − | bool includes( | + | bool includes( InputIt1 first1, InputIt1 last1, |
| − | + | InputIt2 first2, InputIt2 last2 ); | |
}} | }} | ||
{{ddcl list item | num=2 | | {{ddcl list item | num=2 | | ||
| − | template< class | + | template< class InputIt1, class InputIt2 > |
| − | bool includes( | + | bool includes( InputIt1 first1, InputIt1 last1, |
| − | + | InputIt2 first2, InputIt2 last2, Compare comp ); | |
}} | }} | ||
{{ddcl list end}} | {{ddcl list end}} | ||
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{{param list item | first1, last1 | the sorted range of elements to examine}} | {{param list item | first1, last1 | the sorted range of elements to examine}} | ||
{{param list item | first2, last2 | the sorted range of elements to search for}} | {{param list item | first2, last2 | the sorted range of elements to search for}} | ||
| − | {{param list cmp | comp | p1= | + | {{param list cmp | comp | p1=InputIt}} |
{{param list end}} | {{param list end}} | ||
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{{eq fun | {{eq fun | ||
| 1= | | 1= | ||
| − | template<class | + | template<class InputIt1, class InputIt2> |
| − | bool includes( | + | bool includes(InputIt1 first1, InputIt1 last1, |
| − | + | InputIt2 first2, InputIt2 last2) | |
{ | { | ||
for (; first2 != last2; ++first1) | for (; first2 != last2; ++first1) | ||
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} | } | ||
| 2= | | 2= | ||
| − | template<class | + | template<class InputIt1, class InputIt2> |
| − | bool includes( | + | bool includes(InputIt1 first1, InputIt1 last1, |
| − | + | InputIt2 first2, InputIt2 last2, Compare comp) | |
{ | { | ||
for (; first2 != last2; ++first1) | for (; first2 != last2; ++first1) | ||
Revision as of 02:53, 3 August 2012
Template:ddcl list begin <tr class="t-dsc-header">
<td><algorithm>
<td></td> <td></td> </tr> <tr class="t-dcl ">
<td >bool includes( InputIt1 first1, InputIt1 last1,
<td > (1) </td> <td class="t-dcl-nopad"> </td> </tr> <tr class="t-dcl ">
<td >bool includes( InputIt1 first1, InputIt1 last1,
<td > (2) </td> <td class="t-dcl-nopad"> </td> </tr> Template:ddcl list end
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.
Contents |
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) |
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> 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
