std::none_of in C++
Last Updated :
20 Feb, 2023
Returns true if pred returns false for all the elements in the range [first, last] or if the range is empty, and false otherwise.
Syntax :
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
#include <algorithm> // none_of
#include <iostream> // cout
using namespace std;
bool isPrime( int n)
{
if (n <= 1)
return false ;
if (n <= 3)
return true ;
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 ;
}
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;
}
|
Output
Array contains : 2 4 6 8 12 0
No negative elements in the range.
Time Complexity: O(n)
Auxiliary Space: O(1)
Practical Application :
std :: none_of function returns true if certain condition returns false for all the elements in the range [first, last] or if the range is empty, and false otherwise.
1. Check if array contains all even number or odd or both.
Output
Array contains : 2 4 6 8 12 0
Contains even number only
Time Complexity: O(n)
Auxiliary Space: O(1)
2. To check whether array contains all prime number or not.
CPP
#include <algorithm> // none_of
#include <iostream> // cout
using namespace std;
bool isPrime( int n)
{
if (n <= 1)
return false ;
if (n <= 3)
return true ;
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 ;
}
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;
}
|
Output
Array contains : 4 6 8 12 0
All numbers are composite.
Time Complexity: O(n)
Auxiliary Space: O(1)
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