negate

Function Object

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• Data Type and Member Function Indexes
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• Interface
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Unary function object that returns the negation of its argument.

None

#include <functional>
template <class T>
struct negate : public unary_function<T, T>;

negate is a unary function object. Its operator() returns the negation of its argument: true if its argument is false, or false if its argument is true. You can pass a negate object to any algorithm that requires a unary function. For example, the transform algorithm applies a unary operation to the values in a collection and stores the result. negate could be used in that algorithm in the following manner:

vector<int> vec1;
vector<int> vecResult;
.
.
.
transform(vec1.begin(), vec1.end(), vecResult.begin(),
          negate<int>());

After this call to transform, vecResult(n) contains the negation of the element in vec1(n).

template <class T>
struct negate : unary_function<T, T> {
  T operator() (const T&) const;
};

If your compiler does not support default template parameters, then you always need to supply the Allocator template argument. For instance, you need to write:

vector<int, allocator<int> >

instead of:

vector<int>

If your compiler does not support namespaces, then you do not need the using declaration for std.

Function Objects, unary_function