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

Last Updated : 30 May, 2019

The one_of_equal() function in C++ boost library is found under the header 'boost/algorithm/cxx11/one_of.hpp' which tests if exactly one of the elements of a sequence against the value passed is same. It takes a sequence and a value, and returns true if the exactly one of the elements are same in the sequence to the value passed. Syntax:

bool one_of_equal ( InputIterator first, InputIterator last, const &value) or bool one_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 one the elements of the sequence.
R: It is the complete sequence.

Return Value: The function returns true if exactly one of the elements of the sequence is equal to value, else it returns false. Below is the implementation of the above approach: Program-1:

CPP

// C++ program to implement the
// above mentioned function

#include <bits/stdc++.h>
#include <boost/algorithm/cxx11/one_of.hpp>
using namespace std;

// Drivers code
int main()
{

    // Declares the sequence with
    int c[] = { 1, 2, 3 };

    // Run the function
    bool ans = boost::algorithm::one_of_equal(c, 1);

    // Condition to check
    if (ans == 1)
        cout << "exactly one element is 1";
    else
        cout << "exactly one element is not 1";
    return 0;
}

Output:

exactly one element is 1

Program-2:

CPP

// C++ program to implement the
// above mentioned function

#include <bits/stdc++.h>
#include <boost/algorithm/cxx11/one_of.hpp>
using namespace std;

// Drivers code
int main()
{

    // Declares the sequence
    int a[] = { 1, 2, 3, 6 };

    // Run the function
    bool ans
        = boost::algorithm::one_of_equal(a, a + 4, 4);

    // Condition to check
    if (ans == 1)
        cout << "exactly one element is 4";
    else
        cout << "exactly one element is not 4";
    return 0;
}