std::none_of en C++

Devuelve verdadero si pred devuelve falso para todos los elementos del rango [primero, último] o si el rango está vacío y falso en caso contrario.
Sintaxis: 

Template :
bool none_of(InputIterator first, InputIterator last,
                                 UnaryPredicate pred);
first, last
Input iterators to the initial and final positions in
a sequence. The range used is [first, last], which 
contains all the elements between first and last, 
including the element pointed by first but not the
element pointed by last.

pred
Unary function that accepts an element in the range
as argument and returns a value convertible to bool. 
The value returned indicates whether the element 
fulfills the condition checked by this function.
The function shall not modify its argument.
This can either be a function pointer or a function
object. 

Return type :
true if pred returns false for all the elements in 
the range [first, last] or if the range is empty, 
and false otherwise.

// CPP program to illustrate std :: none_of
#include <iostream> // cout
#include <algorithm> // none_of
using namespace std;
 
// function to check whether the
// element is negative or not
bool comp(int a) {  return a < 0;  }
 
// Driver code
int main()
{
    int arr[] = { 2, 4, 6, 8, 12, 0 };
    int n = sizeof(arr)/sizeof(arr[0]);
 
    cout << "Array contains :";
    for (int i = 0; i < n; i++)
        cout << ' ' << arr[i];
    cout << "\n";
 
    if (none_of(arr, arr+n, comp))
        cout << "No negative elements in the range.\n";
    else
        cout << "There is at least one negative"
               " element in the array range.\n";
    return 0;
}

Array contains : 2 4 6 8 12 0
No negative elements in the range.

Aplicación práctica: 
la función std::none_of devuelve verdadero si cierta condición devuelve falso para todos los elementos en el rango [primero, último] o si el rango está vacío, y falso en caso contrario.
1. Compruebe si la array contiene todos los números pares o impares o ambos. 

// CPP program to illustrate std :: none_of
#include <iostream> // cout
#include <algorithm> // none_of
using namespace std;
 
// functions to check whether the
// element is even or odd
bool isEven(int a) { return (a % 2); }
bool isOdd(int a)  { return (a % 2 == 0); }
 
// Driver code
int main()
{
    int arr[] = { 2, 4, 6, 8, 12, 0 };
    int n = sizeof(arr)/sizeof(arr[0]);
 
    cout << "Array contains :";
    for (int i = 0; i < n; i++)
        cout << ' ' << arr[i];
    cout << "\n";
 
    bool even = none_of(arr, arr + n, isEven);
    bool odd =  none_of(arr, arr + n, isOdd);
 
    if ((!even) && (!odd))
        cout << "Contains both even and"
               " odd number\n";
    else if ((!even) && odd)
        cout << "Contains odd number only\n";
    else if (even && (!odd))
        cout << "Contains even number only\n";
    else
        cout << "Array is empty\n";
 
    return 0;
}

Array contains : 2 4 6 8 12 0
Contains even number only

2. Para verificar si la array contiene todos los números primos o no.  

// CPP program to illustrate std :: none_of
#include <algorithm> // none_of
#include <iostream> // cout
using namespace std;
 
// Function reference :
// https://www.geeksforgeeks.org/primality-test-set-
// 1-introduction-and-school-method/
bool isPrime(int n)
{
    // Corner cases
    if (n <= 1)
        return false;
    if (n <= 3)
        return true;
 
    // This is checked so that we can skip
    // middle five numbers in below loop
    if (n % 2 == 0 || n % 3 == 0)
        return false;
 
    for (int i = 5; i * i <= n; i = i + 6)
        if (n % i == 0 || n % (i + 2) == 0)
            return false;
 
    return true;
}
 
// Driver code
int main()
{
    int arr[] = { 4, 6, 8, 12, 0 };
    int n = sizeof(arr) / sizeof(arr[0]);
 
    cout << "Array contains :";
    for (int i = 0; i < n; i++)
        cout << ' ' << arr[i];
    cout << "\n";
 
    if (none_of(arr, arr + n, isPrime))
        cout << "All numbers are composite.\n";
    else
        cout << "There are primes in array \n";
    return 0;
}

Array contains : 4 6 8 12 0
All numbers are composite.

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