Namespace
Varianti

std::all_of, std::any_of, std::none_of

Da cppreference.com.
< cpp‎ | algorithm

 
 
Algoritmo libreria
Funzioni
Original:
Functions
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Non modifica le operazioni di sequenza
Original:
Non-modifying sequence operations
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all_of
any_of
none_of
(C++11)
(C++11)
(C++11)
for_each
count
count_if
mismatch
equal
Modifica delle operazioni di sequenza
Original:
Modifying sequence operations
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Partizionamento operazioni
Original:
Partitioning operations
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Ordinamento delle operazioni (su intervalli ordinati)
Original:
Sorting operations (on sorted ranges)
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Binarie (le operazioni di ricerca sui campi ordinati)
Original:
Binary search operations (on sorted ranges)
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Impostare le operazioni (su intervalli ordinati)
Original:
Set operations (on sorted ranges)
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Heap operazioni
Original:
Heap operations
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Minimo / massimo le operazioni
Original:
Minimum/maximum operations
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Operazioni numeriche
Original:
Numeric operations
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Libreria C
Original:
C library
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Defined in header <algorithm>
template< class InputIt, class UnaryPredicate >
bool all_of( InputIt first, InputIt last, UnaryPredicate p );
(1) (dal C++11)
template< class InputIt, class UnaryPredicate >
bool any_of( InputIt first, InputIt last, UnaryPredicate p );
(2) (dal C++11)
template< class InputIt, class UnaryPredicate >
bool none_of( InputIt first, InputIt last, UnaryPredicate p );
(3) (dal C++11)
1)
Verifica se predicato unario p rendimenti true per tutti gli elementi della gamma [first, last).
Original:
Checks if unary predicate p returns true for all elements in the range [first, last).
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2)
Verifica se predicato unario p rendimenti true per almeno un elemento nel range [first, last).
Original:
Checks if unary predicate p returns true for at least one element in the range [first, last).
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3)
Verifica se predicato unario p rendimenti true per nessun elemento della gamma [first, last).
Original:
Checks if unary predicate p returns true for no elements in the range [first, last).
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Indice

[modifica] Parametri

first, last -
la gamma di elementi da esaminare
Original:
the range of elements to examine
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p - unary predicate .

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.

[modifica] Valore di ritorno

1)
true se unario true predicato ritorna per tutti gli elementi della gamma, false altrimenti. Restituisce true se il campo è vuoto.
Original:
true if unary predicate returns true for all elements in the range, false otherwise. Returns true if the range is empty.
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2)
true se unario true predicato restituisce per almeno un elemento della gamma, false altrimenti. Restituisce false se il campo è vuoto.
Original:
true if unary predicate returns true for at least one element in the range, false otherwise. Returns false if the range is empty.
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3)
true se unario true predicato ritorna per non elementi nell'intervallo, false altrimenti. Restituisce true se il campo è vuoto.
Original:
true if unary predicate returns true for no elements in the range, false otherwise. Returns true if the range is empty.
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[modifica] Complessità

Al massimo last - first applicazioni del predicato
Original:
At most last - first applications of the predicate
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[modifica] Possibile implementazione

First version
template< class InputIt, class UnaryPredicate >
bool all_of(InputIt first, InputIt last, UnaryPredicate p)
{
    for (; first != last; ++first) {
        if (!p(*first)) return false;
    }
    return true;
}
Second version
template< class InputIt, class UnaryPredicate >
bool any_of(InputIt first, InputIt last, UnaryPredicate p)
{
    for (; first != last; ++first) {
        if (p(*first)) return true;
    }
    return false;
}
Third version
template< class InputIt, class UnaryPredicate >
bool none_of(InputIt first, InputIt last, UnaryPredicate p)
{
    for (; first != last; ++first) {
        if (p(*first)) return false;
    }
    return true;
}

[modifica] Esempio

#include <vector>
#include <numeric>
#include <algorithm>
#include <iterator>
#include <iostream>
#include <functional>
 
int main()
{
    std::vector<int> v(10, 2);
    std::partial_sum(v.cbegin(), v.cend(), v.begin());
    std::cout << "Among the numbers: ";
    std::copy(v.cbegin(), v.cend(), std::ostream_iterator<int>(std::cout, " "));
    std::cout << '\n';
 
    if (std::all_of(v.cbegin(), v.cend(), [](int i){ return i % 2 == 0; })) {
        std::cout << "All numbers are even\n";
    }
    if (std::none_of(v.cbegin(), v.cend(), std::bind(std::modulus<int>(), 
                                                     std::placeholders::_1, 2))) {
        std::cout << "None of them are odd\n";
    }
    struct DivisibleBy
    {
        const int d;
        DivisibleBy(int n) : d(n) {}
        bool operator()(int n) const { return n % d == 0; }
    };
 
    if (std::any_of(v.cbegin(), v.cend(), DivisibleBy(7))) {
        std::cout << "At least one number is divisible by 7\n";
    }
}

Output:

Among the numbers: 2 4 6 8 10 12 14 16 18 20 
All numbers are even
None of them are odd
At least one number is divisible by 7