boost::algorithm::none_of() in C++ library

The none_of() function in C++ boost library is found under the header ‘boost/algorithm/cxx11/none_of.hpp’ which tests all the elements of a sequence and returns true if all of them do not share a property. It takes a sequence and a predicate, and returns true if the predicate returns false when applied to every element in the sequence.

Syntax:

bool none_of ( InputIterator first, InputIterator last, Predicate p )
or
bool none_of ( const Range &R, Predicate p)

Parameters: The function accepts parameters as described below:

  • first: It specifies the input iterators to the initial positions in a sequence.
  • second: It specifies the input iterators to the final positions in a sequence.
  • p: It specifies a unary predicate function that accepts an element and returns a bool.
  • R: It is the complete sequence.

Return Value: The function returns true if the given predicate is false for all the elements of the sequence, else it returns false.

Below is the implementation of the above approach:

Program-1:

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// C++ program to implement the
// above mentioned function
  
#include <bits/stdc++.h>
#include <boost/algorithm/cxx11/none_of.hpp>
using namespace std;
// using boost::algorithm;
  
// Predicate function to check if
// the element is odd or not
bool isOdd(int i)
{
    return i % 2 == 1;
}
  
// Drivers code
int main()
{
  
    // Declares the sequence with
    // 5 length and none elements as 1
    // [1, 1, 1, 1, 1]
    vector<int> c(5, 1);
  
    // Run the function with second syntax
    bool ans
        = boost::algorithm::none_of(c, isOdd);
  
    // Condition to check
    if (ans == 1)
        cout << "all are not odd";
    else
        cout << "all are odd";
    return 0;
}

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Output:

all are odd

Program-2:

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// C++ program to implement the
// above mentioned function
  
#include <bits/stdc++.h>
#include <boost/algorithm/cxx11/none_of.hpp>
using namespace std;
// using boost::algorithm;
  
// Predicate function to check if
// the elements are less than 7 or not
bool noneLessThanSeven(int i)
{
    return i < 7;
}
  
// Drivers code
int main()
{
  
    // Declares the sequence
    int a[] = { 1, 2, 5, 6 };
  
    // Run the function with first syntax
    bool ans
        = boost::algorithm::none_of(a, a + 4,
                                    noneLessThanSeven);
  
    // Condition to check
    if (ans == 1)
        cout << "all greater than 7";
    else
        cout << "all smaller than 7";
    return 0;
}

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Output:

all smaller than 7

Reference: https://www.boost.org/doc/libs/1_70_0/libs/algorithm/doc/html/the_boost_algorithm_library/CXX11/none_of.html



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