std::equal — cppreference.com

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Déclaré dans l'en-tête `<algorithm>`
`template< class InputIt1, class InputIt2 > bool equal( InputIt1 first1, InputIt1 last1, InputIt2 first2 );`	(1)
`template< class InputIt1, class InputIt2, class BinaryPredicate > bool equal( InputIt1 first1, InputIt1 last1, InputIt2 first2, BinaryPredicate p );`	(2)

Retours true si les éléments sont les mêmes dans les deux gammes: l'une définie par [first1, last1) et un autre à partir de first2. La première version de la fonction utilise operator== de comparer les éléments, la seconde utilise le prédicat binaire donné p .

Original:

Returns true if the elements are the same in two ranges: one defined by [first1, last1) and another starting at first2. The first version of the function uses operator== to compare the elements, the second uses the given binary predicate p.

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Paramètres

first1, last1	-	la première plage des éléments de comparaison Original: the first range of the elements to compare The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
first2	-	au début de la seconde plage des éléments de comparaison Original: beginning of the second range of the elements to compare 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 objects of types `InputIt1` and `InputIt2` can be dereferenced and then implicitly converted to `Type1` and `Type2` respectively.
Type requirements
-`InputIt1, InputIt2` must meet the requirements of `InputIterator`.

Retourne la valeur

true si les éléments dans les deux gammes sont égaux

Original:

true if the elements in the two ranges are equal

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Notes

std::equal peut pas être utilisé pour comparer les intervalles formés par les itérateurs de std::unordered_set, std::unordered_multiset, std::unordered_map, ou std::unordered_multimap parce que l'ordre dans lequel les éléments sont stockés dans les récipients peuvent être différents, même si les deux récipients stocker les mêmes éléments .

Original:

std::equal may not be used to compare the ranges formed by the iterators from std::unordered_set, std::unordered_multiset, std::unordered_map, or std::unordered_multimap because the order in which the elements are stored in those containers may be different even if the two containers store the same elements.

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{{{1}}}

Original:

{{{2}}}

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Complexité

Tout au plus last1 - first1 applications du prédicat

Original:

At most last1 - first1 applications of the predicate

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Mise en œuvre possible

First version
template<class InputIt1, class InputIt2> bool equal(InputIt1 first1, InputIt1 last1, InputIt2 first2) { for (; first1 != last1; ++first1, ++first2) { if (!(first1 == first2)) { return false; } } return true; }
Second version
template<class InputIt1, class InputIt2, class BinaryPredicate> bool equal(InputIt1 first1, InputIt1 last1, InputIt2 first2, BinaryPredicate p) { for (; first1 != last1; ++first1, ++first2) { if (!p(first1, first2)) { return false; } } return true; }

First version

template<class InputIt1, class InputIt2>
bool equal(InputIt1 first1, InputIt1 last1, 
           InputIt2 first2)
{
    for (; first1 != last1; ++first1, ++first2) {
        if (!(*first1 == *first2)) {
            return false;
        }
    }
    return true;
}

Second version

template<class InputIt1, class InputIt2, class BinaryPredicate>
bool equal(InputIt1 first1, InputIt1 last1, 
           InputIt2 first2, BinaryPredicate p)
{
    for (; first1 != last1; ++first1, ++first2) {
        if (!p(*first1, *first2)) {
            return false;
        }
    }
    return true;
}

Exemple

Le code suivant utilise equal() pour tester si une chaîne est un palindrome

Original:

The following code uses equal() to test if a string is a palindrome

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#include <iostream>
#include <algorithm>
#include <string>

void test(const std::string& s)
{
    if(std::equal(s.begin(), s.begin() + s.size()/2, s.rbegin())) {
        std::cout << "\"" << s << "\" is a palindrome\n";
    } else {
        std::cout << "\"" << s << "\" is not palindrome\n";
    }
}
int main()
{
    test("radar");
    test("hello");
}

Résultat :

"radar" is a palindrome
"hello" is not palindrome


find find_if find_if_not (C++11)	trouve le premier élément répondant à des critères spécifiques Original: finds the first element satisfying specific criteria The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (fonction générique) [edit]

lexicographical_compare	renvoie vrai si une plage est lexicographiquement inférieur à un autre Original: returns true if one range is lexicographically less than another The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (fonction générique) [edit]

mismatch	trouve la première position dans laquelle deux plages différentes Original: finds the first position where two ranges differ The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (fonction générique) [edit]

search	recherches pour une série d'éléments Original: searches for a range of elements The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (fonction générique) [edit]