std::adjacent_find - cppreference.com

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Definido no cabeçalho `<algorithm>`

`template< class ForwardIt > ForwardIt adjacent_find( ForwardIt first, ForwardIt last );`	(1)

`template< class ForwardIt, BinaryPredicate p > ForwardIt adjacent_find( ForwardIt first, ForwardIt last, BinaryPredicate p );`	(2)

Pesquisa o [first, last) faixa por duas consecutivas elementos idênticos. A primeira versão utiliza operator== para comparar os elementos, a segunda versão usa o predicado binário dado p.

Original:

Searches the range [first, last) for two consecutive identical elements. The first version uses operator== to compare the elements, the second version uses the given binary predicate p.

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Parâmetros

first, last	-	a gama de elementos para examinar Original: the range of elements to examine The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
p	-	binary predicate which returns `true` if the elements should be treated as equal. The signature of the predicate function should be equivalent to the following: `bool pred(const Type1 &a, const Type2 &b);` The signature does not need to have `const &`, but the function must not modify the objects passed to it. The types `Type1` and `Type2` must be such that an object of type `ForwardIt` can be dereferenced and then implicitly converted to both of them.
Type requirements
-`ForwardIt` must meet the requirements of `ForwardIterator`.

Valor de retorno

um iterador para o primeiro dos elementos idênticos. Se não houver tais elementos são encontrados, last é devolvido

Original:

an iterator to the first of the identical elements. If no such elements are found, last is returned

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Complexidade

Exatamente as aplicações menores de (result - first) e ((last - 1) - first) do predicado onde result é o valor de retorno.

Original:

Exactly the smaller of (result - first) and ((last - 1) - first) applications of the predicate where result is the return value.

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Possível implementação

First version
template<class ForwardIt> ForwardIt adjacent_find(ForwardIt first, ForwardIt last) { if (first == last) { return last; } ForwardIt next = first; ++next; for (next != last; ++next, ++first) { if (first == next) { return first; } } return last; }
Second version
template<class ForwardIt, BinaryPredicate p> ForwardIt adjacent_find(ForwardIt first, ForwardIt last, BinaryPredicate p) { if (first == last) { return last; } ForwardIt next = first; ++next; for (next != last; ++next, ++first) { if (p(first, next)) { return first; } } return last; }

First version

template<class ForwardIt>
ForwardIt adjacent_find(ForwardIt first, ForwardIt last)
{
    if (first == last) {
        return last;
    }
    ForwardIt next = first;
    ++next;
    for (next != last; ++next, ++first) {
        if (*first == *next) {
            return first;
        }
    }
    return last;
}

Second version

template<class ForwardIt, BinaryPredicate p>
ForwardIt adjacent_find(ForwardIt first, ForwardIt last, 
                        BinaryPredicate p)
{
    if (first == last) {
        return last;
    }
    ForwardIt next = first;
    ++next;
    for (next != last; ++next, ++first) {
        if (p(*first, *next)) {
            return first;
        }
    }
    return last;
}

Exemplo

O código a seguir encontra um par de inteiros equivalentes em uma matriz de intergers .

Original:

The following code finds a pair of equivalent integers in an array of intergers.

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#include <algorithm>
#include <iostream>
 
int main()
{
    std::vector<int> v1{0, 1, 2, 3, 40, 40, 5};
 
    std::vector<int>::iterator result;
    result = std::adjacent_find(v1.begin(), v1.end());
 
    if (result == v1.end()) {
        std::cout << "no matching adjacent elements";
    } else {
        std::cout << "match at: " << std::distance(v1.begin(), result);
    }
}

Saída:

Veja também


	removes consecutive duplicate elements in a range (modelo de função) [edit]