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;}
};
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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;
}
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Output:
The first different element is 20
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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) |
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