Function Object
Unary function object that returns true if its argument is false.
#include <functional>
template <class T> struct logical_not : unary_function<T, bool> ;
logical_not is a unary function object. Its operator() returns true if its argument is false. You can pass a logical_not object to any algorithm that requires a unary function. For example, the replace_if algorithm replaces an element with another value if the result of a unary operation is true. logical_not is used in that algorithm in the following manner:
vector<int> vec1;
. . . void replace_if(vec1.begin(), vec1.end(), logical_not<int>(),1);
This call to replace_if replaces all zeros in the vec1 with "1".
template <class T>
struct logical_not : unary_function<T, bool> { typedef typename unary_function<T, bool>::argument_type argument_type; typedef typename unary_function<T, bool>::result_type result_type; bool operator() (const T&) const; };
If your compiler does not support default template parameters, you will need to always supply the Allocator template arguement. For instance, you will have to write :
vector<int, allocator>
instead of :
vector<int>
Function Objects, unary_function