function template
<functional>
std::not1
template <class Predicate> unary_negate<Predicate> not1 (const Predicate& pred);
Return negation of unary function object
Constructs a unary function object (of a unary_negate type) that returns the opposite of pred (as returned by operator !).
It is defined with the same behavior as:
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template <class Predicate> unary_negate<Predicate> not1 (const Predicate& pred)
{
return unary_negate<Predicate>(pred);
}
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Parameters
- pred
- Unary function object of a class type with member argument_type defined.
Return value
An unary function object with the opposite behavior of pred.
See unary_negate.
Example
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// not1 example
#include <iostream> // std::cout
#include <functional> // std::not1
#include <algorithm> // std::count_if
struct IsOdd {
bool operator() (const int& x) const {return x%2==1;}
typedef int argument_type;
};
int main () {
int values[] = {1,2,3,4,5};
int cx = std::count_if (values, values+5, std::not1(IsOdd()));
std::cout << "There are " << cx << " elements with even values.\n";
return 0;
}
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Output:
There are 2 elements with even values.
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See also
- not2
- Return negation of binary function object (function template)
- unary_negate
- Negate unary function object class (class template)