Negators
Utilities » Function Objects
Collaboration diagram for Negators:

## Functions

template<typename _Predicate >
constexpr unary_negate< _Predicate > | std::not1 (const _Predicate &__pred)
template<typename _Predicate >
constexpr binary_negate< _Predicate > | std::not2 (const _Predicate &__pred)

## Detailed Description

The function templates `not1` and `not2` are function object adaptors, which each take a predicate functor and wrap it in an instance of `unary_negate` or `binary_negate`, respectively. Those classes are functors whose `operator()` evaluates the wrapped predicate function and then returns the negation of the result.

For example, given a vector of integers and a trivial predicate,

struct IntGreaterThanThree
: public std::unary_function<int, bool>
{
bool operator() (int x) const { return x > 3; }
};
std::find_if (v.begin(), v.end(), not1(IntGreaterThanThree()));
std::not1
constexpr unary_negate< _Predicate > not1(const _Predicate &__pred)
One of the negation functors.
Definition: stl_function.h:1041
std::unary_function
Definition: stl_function.h:118

The call to `find_if` will locate the first index (i) of `v` for which `!(v[i] > 3)` is true.

The not1/unary_negate combination works on predicates taking a single argument. The not2/binary_negate combination works on predicates taking two arguments.

Deprecated:
  Deprecated in C++17, no longer in the standard since C++20. Use `not_fn` instead.

## Function Documentation

## not1()

template<typename _Predicate >

constexpr unary_negate<_Predicate> std::not1 | ( | const _Predicate & | __pred | ) |

inline constexpr

One of the negation functors.

Definition at line 1041 of file stl_function.h.

## not2()

template<typename _Predicate >

constexpr binary_negate<_Predicate> std::not2 | ( | const _Predicate & | __pred | ) |

inline constexpr

One of the negation functors.

Definition at line 1069 of file stl_function.h.