std::adjacent_find – cppreference.com

Aus cppreference.com

definiert in Header `<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)

Durchsucht den Bereich [first, last) für zwei aufeinanderfolgende identische Elemente. Die erste Version verwendet operator== um die Elemente zu vergleichen, verwendet die zweite Version des gegebenen binären Prädikats 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.

The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

Parameter

first, last	-	das Spektrum der Elemente zu untersuchen 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`.

Rückgabewert

ein Iterator auf der ersten der gleiche Elemente. Wenn keine Elemente gefunden werden, wird last zurückgegeben

Original:

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

The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

Komplexität

Genau die kleinere der (result - first) und ((last - 1) - first) Anwendungen des Prädikats, wo result ist der Rückgabewert .

Original:

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

The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

Mögliche Implementierung

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;
}

Beispiel

Der folgende Code findet ein Paar äquivalenter ganze Zahlen in einem Array von intergers .

Original:

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

The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

#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);
    }
}

Output:

Siehe auch


	removes consecutive duplicate elements in a range (Funktions-Template) [edit]