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

Last Updated : 30 May, 2019

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

bool all_of ( InputIterator first, InputIterator last, Predicate p ) or bool all_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 all the elements 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>

// using boost::algorithm;
#include <boost/algorithm/cxx11/all_of.hpp>

using namespace std;

// 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 all elements as 1
    // [1, 1, 1, 1, 1]
    vector<int> c(5, 1);

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

    // Condition to check
    if (ans == 1)
        cout << "ALl elements are odd";
    else
        cout << "All elements are even";
    return 0;
}

Output:

ALl elements are odd

Program-2:

CPP

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

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

// using boost::algorithm;

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

// Drivers code
int main()
{

    // Declares the sequence
    int a[] = { 1, 2, 5, 6 };

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

    // Condition to check
    if (ans == 1)
        cout << "ALl elements are less than 7";
    else
        cout << "All elements are not less than 7";
    return 0;
}