std::find_end

From Cppreference

Defined in header `<algorithm>`

template< class ForwardIterator1, class ForwardIterator2 > ForwardIterator1 find_end( ForwardIterator1 first, ForwardIterator1 last, ForwardIterator2 s_first, ForwardIterator2 s_last );	(1)

template< class ForwardIterator1, class ForwardIterator2, class BinaryPredicate > ForwardIterator1 find_end( ForwardIterator1 first, ForwardIterator1 last, ForwardIterator2 s_first, ForwardIterator2 s_last, BinaryPredicate p );	(2)

Searches for the last subsequence of elements [s_first, s_last) in the range [first, last). The first version uses operator== to compare the elements, the second version uses the given binary predicate p.

template<class ForwardIterator1, class ForwardIterator2>
ForwardIterator1 find_end(ForwardIterator1 first, ForwardIterator1 last,
                          ForwardIterator2 s_first, ForwardIterator2 s_last)
{
    if (s_first == s_last)
        return last;
    ForwardIterator1 result = last;
    while (1) {
        ForwardIterator1 new_result = std::search(first, last, s_first, s_last);
        if (new_result == last) {
             return result;
        } else {
            result = new_result;
            first = result;
            ++first;
        }
    }
    return result;
}

Second version

template<class ForwardIterator1, class ForwardIterator2>
ForwardIterator1 find_end(ForwardIterator1 first, ForwardIterator1 last,
                          ForwardIterator2 s_first, ForwardIterator2 s_last,
                          BinaryPredicate p)
{
    if (s_first == s_last)
        return last;
    ForwardIterator1 result = last;
    while (1) {
        ForwardIterator1 new_result = std::search(first, last, s_first, s_last, p);
        if( new_result == last ) {
            return result;
        } else {
            result = new_result;
            first = result;
            ++first;
        }
    }
    return result;
}

[edit] Example

The following code uses find_end() to search for two different sequences of numbers.

#include <algorithm>
#include <iostream>
#include <vector>
 
int main()
{
    std::vector<int> v{1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4};
    std::vector<int>::iterator result;
 
    std::vector<int> t1{1, 2, 3};
 
    result = std::find_end(v.begin(), v.end(), t1.begin(), t1.end());
    if (result == v.end()) {
        std::cout << "subsequence not found\n";
    } else {
        std::cout << "last subsequence is at: "
                  << std::distance(v.begin(), result) << "\n";
    }
 
    std::vector<int> t2{4, 5, 6};
    result = std::find_end(v.begin(), v.end(), t2.begin(), t2.end());
    if (result == v.end()) {
        std::cout << "subsequence not found\n";
    } else {
        std::cout << "last subsequence is at: " 
                  << std::distance(v.begin(), result) << "\n";
    }
}

Output:

last subsequence is at: 8
subsequence not found

[edit] See also

adjacent_find

finds two identical (or some other relationship) items adjacent to each other
(function template)

find find_if find_if_not (C++11)

finds the first element satisfying specific criteria
(function template)

find_first_of

searches for any one of a set of elements
(function template)

search_n

searches for a number consecutive copies of an element in a range
(function template)

std::find_end

From Cppreference

Contents

[edit] Parameters

[edit] Return value

[edit] Complexity

[edit] Equivalent function

[edit] Example

[edit] See also