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:
// 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;
} |
all are odd
Program-2:
// 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;
} |
all smaller than 7