class template
<functional>
std::negate
template <class T> struct negate;
Negative function object class
Unary function object class whose call returns the result of negating its argument (as returned by the unary operator -).
Negating a value returns the same value with the opposite sign.
Generically, function objects are instances of a class with member function operator() defined. This member function allows the object to be used with the same syntax as a function call.
It is defined with the same behavior as:
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template <class T> struct negate : unary_function <T,T> {
T operator() (const T& x) const {return -x;}
};
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template <class T> struct negate {
T operator() (const T& x) const {return -x;}
typedef T argument_type;
typedef T result_type;
};
Objects of this class can be used on standard algorithms such as transform .
Template parameters
- T
- Type of the argument and return type of the functional call.
The type shall support the operation (unary operator-).
Member types
| member type | definition | notes |
|---|
| argument_type | T | Type of the argument in member operator() |
| result_type | bool | Type returned by member operator() |
Member functions
- T operator() (const T& x)
- Member function returning the negation of its argument (
-x).
Example
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// negate example
#include <iostream> // std::cout
#include <functional> // std::negate
#include <algorithm> // std::transform
int main () {
int numbers[]={10,-20,30,-40,50};
std::transform (numbers, numbers+5, numbers, std::negate<int>());
for (int i=0; i<5; i++)
std::cout << numbers[i] << ' ';
std::cout << '\n';
return 0;
}
Output:
See also
- plus
- Addition function object class (class template)
- minus
- Subtraction function object class (class template)
- multiplies
- Multiplication function object class (class template)
- divides
- Division function object class (class template)
- modulus
- Modulus function object class (class template)
- equal_to
- Function object class for equality comparison (class template)