std::find, std::find_if, std::find_if_not

 

C++

Linguaggio

Concetti

Libreria di Utilità

Stringhe

Contenitori

Algoritmi

Iteratori

Libreria matematca

Input/output

Localizzazione

Espressioni regolari (C++11)

Operazioni atomicche (C++11)

Multithreading (C++11)

 

Algoritmo libreria

Funzioni Original: Functions The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
Non modifica le operazioni di sequenza Original: Non-modifying sequence operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
all_of any_of none_of (C++11) (C++11) (C++11) for_each count count_if mismatch equal	find find_if find_if_not (C++11) find_end find_first_of adjacent_find search search_n
Modifica delle operazioni di sequenza Original: Modifying sequence operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
copy copy_if (C++11) copy_n (C++11) copy_backward move (C++11) move_backward (C++11) fill fill_n transform generate generate_n remove remove_if remove_copy remove_copy_if	replace replace_if replace_copy replace_copy_if swap swap_ranges iter_swap reverse reverse_copy rotate rotate_copy random_shuffle shuffle   (C++11) unique unique_copy
Partizionamento operazioni Original: Partitioning operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
is_partitioned (C++11) partition partition_copy (C++11)	stable_partition partition_point (C++11)
Ordinamento delle operazioni (su intervalli ordinati) Original: Sorting operations (on sorted ranges) The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
is_sorted (C++11) is_sorted_until (C++11) sort	partial_sort partial_sort_copy stable_sort nth_element
Binarie (le operazioni di ricerca sui campi ordinati) Original: Binary search operations (on sorted ranges) The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
lower_bound upper_bound	binary_search equal_range
Impostare le operazioni (su intervalli ordinati) Original: Set operations (on sorted ranges) The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
merge inplace_merge includes	set_difference set_intersection set_symmetric_difference set_union
Heap operazioni Original: Heap operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
is_heap is_heap_until (C++11) make_heap	push_heap pop_heap sort_heap
Minimo / massimo le operazioni Original: Minimum/maximum operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
max max_element min min_element minmax (C++11) minmax_element (C++11)	lexicographical_compare is_permutation (C++11) next_permutation prev_permutation
Operazioni numeriche Original: Numeric operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
iota (C++11) accumulate inner_product	adjacent_difference partial_sum
Libreria C Original: C library The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
qsort	bsearch

 

Defined in header <algorithm>
template< class InputIt, class T > InputIt find( InputIt first, InputIt last, const T& value );	(1)
template< class InputIt, class UnaryPredicate > InputIt find_if( InputIt first, InputIt last,                  UnaryPredicate p );	(2)
template< class InputIt, class UnaryPredicate > InputIt find_if_not( InputIt first, InputIt last,                      UnaryPredicate q );	(3)	(dal C++11)

Queste funzioni trovare il primo elemento nella [first, last) gamma che soddisfa criteri specifici:

Original:

These functions find the first element in the range [first, last) that satisfies specific criteria:

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1. find ricerche di un elemento pari a value

Original:

1. find searches for an element equal to value

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2. find_if cerca un elemento per il quale predicato p ritorna true

Original:

2. find_if searches for an element for which predicate p returns true

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3. find_if_not cerca elemento per il quale predicato q ritorna false

Original:

3. find_if_not searches for element for which predicate q returns false

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Parametri

first, last	-	la gamma di elementi da esaminare 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.
value	-	valore per confrontare gli elementi Original: value to compare the elements to The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
p	-	unary predicate which returns ​true per l'elemento richiesto Original: for the required element The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. . The signature of the predicate function should be equivalent to the following:  bool pred(const Type &a); The signature does not need to have const &, but the function must not modify the objects passed to it. The type Type must be such that an object of type InputIt can be dereferenced and then implicitly converted to Type. ​
q	-	unary predicate which returns ​false per l'elemento richiesto Original: for the required element The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. . The signature of the predicate function should be equivalent to the following:  bool pred(const Type &a); The signature does not need to have const &, but the function must not modify the objects passed to it. The type Type must be such that an object of type InputIt can be dereferenced and then implicitly converted to Type. ​
Type requirements
- InputIt must meet the requirements of InputIterator.

Valore di ritorno

Iteratore al primo elemento che soddisfa la condizione o last se tale elemento non viene trovato.

Original:

Iterator to the first element satisfying the condition or last if no such element is found.

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Complessità

Al massimo last - first applicazioni del predicato

Original:

At most last - first applications of the predicate

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Possibile implementazione

First version
template<class InputIt, class T> InputIt find(InputIt first, InputIt last, const T& value) { for (; first != last; ++first) { if (*first == value) { return first; } } return last; }
Second version
template<class InputIt, class UnaryPredicate> InputIt find_if(InputIt first, InputIt last, UnaryPredicate p) { for (; first != last; ++first) { if (p(*first)) { return first; } } return last; }
Third version
template<class InputIt, class UnaryPredicate> InputIt find_if_not(InputIt first, InputIt last, UnaryPredicate q) { for (; first != last; ++first) { if (!q(*first)) { return first; } } return last; }

Se non si dispone di C + +11, l'equivalente di std::find_if_not è quello di utilizzare std::find_if con il predicato negato.

Original:

If you do not have C++11, an equivalent to std::find_if_not is to use std::find_if with the negated predicate.

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template<class InputIt, class UnaryPredicate> InputIt find_if_not(InputIt first, InputIt last, UnaryPredicate q) { return std::find_if(first, last, std::not1(q)); }

Esempio

Nell'esempio seguente vengono individuati un numero intero in un vettore di interi .

Original:

The following example finds an integer in a vector of integers.

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#include <iostream>
#include <algorithm>
#include <vector>
 
int main()
{
    int n1 = 3;
    int n2 = 5;
 
    std::vector<int> v{0, 1, 2, 3, 4};
 
    auto result1 = std::find(v.begin(), v.end(), n1);
    auto result2 = std::find(v.begin(), v.end(), n2);
 
    if (result1 != v.end()) {
        std::cout << "v contains: " << n1 << '\n';
    } else {
        std::cout << "v does not contain: " << n1 << '\n';
    }
 
    if (result2 != v.end()) {
        std::cout << "v contains: " << n2 << '\n';
    } else {
        std::cout << "v does not contain: " << n2 << '\n';
    }
}

Output:

v contains: 3
v does not contain: 5

Vedi anche

adjacent_find	trova due identici (o qualche altra relazione) elementi adiacenti l'uno all'altro Original: finds two identical (or some other relationship) items adjacent to each other The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (funzione di modello)
find_end	trova l'ultima sequenza di elementi di un certo intervallo Original: finds the last sequence of elements in a certain range The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (funzione di modello)
find_first_of	searches for any one of a set of elements (funzione di modello)
mismatch	trova la prima posizione in cui due intervalli diversi 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. (funzione di modello)
search	searches for a range of elements (funzione di modello)