not_equal_to


class template
<functional> 
template <class T> struct not_equal_to;

Function object class for non-equality comparison

This class defines function objects for the non-equality comparison operation.

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 regular function call, and therefore it can be used in templates instead of a pointer to a function.

not_equal_to has its operator() member defined such that it returns true if its two arguments do not compare equal to each other using operator!=, and false otherwise.

This class is derived from binary_function and is defined as:

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template <class T> struct not_equal_to : binary_function <T,T,bool> {
  bool operator() (const T& x, const T& y) const
    {return x!=y;}
};


Objects of this class can be used with some standard algorithms such as mismatch, search or unique.

Members

T operator() (const T& x, const T& y)
Member function returning the result of the comparison x!=y.


Example

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// not_equal_to example
#include <iostream>
#include <functional>
#include <algorithm>
using namespace std;

int main () {
  int numbers[]={10,10,10,20,20};
  int* pt = adjacent_find ( numbers, numbers+5, not_equal_to<int>() ) +1 ;
  cout << "The first different element is " << *pt << endl;
  return 0;
}


Output:

The first different element is 20


See also

equal_to Function object class for equality comparison (class template)
greater Function object class for greater-than inequality comparison (class template)
less Function object class for less-than inequality comparison (class template)
greater_equal Function object class for greater-than-or-equal-to comparison (class template)
less_equal Function object class for less-than-or-equal-to comparison (class template)
binary_function Binary function object base class (class template)