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

The none_of_equal() function in C++ boost library is found under the header boost/algorithm/cxx11/none_of.hpp which tests all the elements of a sequence against the value passed in the parameter and returns true if all the elements of the sequence are not equal to the value passed. It takes a sequence and a value, and returns true if none of the elements are equal to the value in the sequence.

Syntax:

bool none_of_equal ( InputIterator first, InputIterator last, const &value)
or
bool none_of_equal ( const Range &R, const &value)

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.
  • value: It specifies a value which is to be checked against for none the elements of the sequence.
  • R: It is the complete sequence.

Return Value: The function returns true if none of the elements of the sequence is equal to value, 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;
  
// 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
    bool ans
        = boost::algorithm::none_of_equal(c, 1);
  
    // Condition to check
    if (ans == 1)
        cout << "all not equal to 1";
    else
        cout << "all equals to 1";
    return 0;
}

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Output:

all equals to 1

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;
  
// Drivers code
int main()
{
  
    // Declares the sequence
    int a[] = { 1, 2, 5, 6 };
  
    // Run the function
    bool ans
        = boost::algorithm::none_of_equal(a, a + 4, 4);
  
    // Condition to check
    if (ans == 1)
        cout << "all not equal to 4";
    else
        cout << "all equal to 4";
    return 0;
}

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Output:

all not equal to 4

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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