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

The any_of() function in C++ boost library is found under the header 'boost/algorithm/cxx11/any_of.hpp' which tests the elements of a sequence and returns true if they any of the elements share the property given. It takes a sequence and a predicate, and returns true if the predicate returns true for any given element in the sequence. Syntax:

bool any_of ( InputIterator first, InputIterator last, Predicate p ) or bool any_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 true on any of the element of the sequence, 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/any_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
    int c[] = { 1, 2, 3 };

    // Run the function with second syntax
    bool ans = boost::algorithm::any_of(c, isOdd);

    // Condition to check
    if (ans == 1)
        cout << "at least one element is odd";
    else
        cout << "all elements are even";
    return 0;
}

Output:

at least one element is odd

Program-2:

CPP

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

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

// Predicate function to check if
// the elements are less than 7 or not
bool anyLessThanSeven(int i)
{
    return i < 7;
}

// Drivers code
int main()
{

    // Declares the sequence
    int a[] = { 1, 2, 10, 8 };

    // Run the function with first syntax
    bool ans
        = boost::algorithm::any_of(a, a + 4,
                                   anyLessThanSeven);

    // Condition to check
    if (ans == 1)
        cout << "at least one element is less than 7";
    else
        cout << "all elements are not less than 7";
    return 0;
}

Output:

at least one element is less than 7

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

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