home | help 
std::not1(3)		       C++ Standard Libary		    std::not1(3)

NAME
     std::not1 - std::not1

Synopsis
	Defined in header <functional>
	template<  class  Predicate  >					  (until
     C++14)
	std::unary_negate<Predicate> not1( const Predicate& pred );
	template< class  Predicate  >					  (since
     C++14)
	constexpr  std::unary_negate<Predicate>  not1( const Predicate&  (depre-
     cated in C++17)
	pred ); 							(removed
     in C++20)

	std::not1  is a helper function to create a function object that returns
     the
	complement of the unary predicate function passed. The	function  object
     created is of
	type std::unary_negate<Predicate>.

	The  unary predicate type must define a member type, argument_type, that
     is
	convertible to the predicate's parameter type. The  unary  function  ob-
     jects obtained
	from  std::ref,  std::cref,  std::negate, std::logical_not, std::mem_fn,
     std::function,
	std::hash, or from another call to std::not1 have this type defined,  as
     are function
	objects derived from the deprecated std::unary_function.

Parameters
	pred - unary predicate

Return value
	std::not1  returns  an object of type std::unary_negate<Predicate>, con-
     structed with
	pred.

Exceptions
	(none)

Example
     // Run this code

      #include <algorithm>
      #include <functional>
      #include <iostream>
      #include <iterator>
      #include <numeric>
      #include <vector>

      struct LessThan7 : std::unary_function<int, bool>
      {
	  bool operator()(int i) const { return i < 7; }
      };

      int main()
      {
	  std::vector<int> v(10);
	  std::iota(std::begin(v), std::end(v), 0);

	  std::cout << std::count_if(begin(v),	end(v),  std::not1(LessThan7()))
     << '\n';

	  // the same as above using std::function
	  std::function<bool(int)> less_than_9 = [](int x) { return x < 9; };
	  std::cout  <<  std::count_if(begin(v), end(v), std::not1(less_than_9))
     << '\n';
      }

Output:
      3
      1

See also
	not_fn		      creates a function object that returns the comple-
     ment of the
	(C++17) 	      result of the function object it holds
			      (function template)
	unary_negate	      wrapper function object returning  the  complement
     of the unary
	(deprecated in C++17) predicate it holds
	(removed in C++20)    (class template)
	function	       wraps  callable	object of any copy constructible
     type with
	(C++11) 	      specified function call signature
			      (class template)
	move_only_function    wraps callable object of any type  with  specified
     function call
	(C++23) 	      signature
			      (class template)
	not2		      constructs custom std::binary_negate object
	(deprecated in C++17) (function template)
	(removed in C++20)
	ptr_fun 	       creates	an  adaptor-compatible	function  object
     wrapper from a
	(deprecated in C++11) pointer to function
	(removed in C++17)    (function template)
	unary_function	      adaptor-compatible unary function base class
	(deprecated in C++11) (class template)
	(removed in C++17)

http://cppreference.com 	   2024.06.10			    std::not1(3)
home | help