## not_equal_to

    Function Object

- Summary
- Data Type and Member Function Indexes
- Synopsis
- Description
- Interface
- Warnings
- See Also

### Summary

A binary function object that returns `true` if its first argument is not equal to its second.

### Data Type and Member Function Indexes
(exclusive of constructors and destructors)

None

### Synopsis

    #include <functional>
    template <class T>
    struct not_equal_to : public binary_function<T, T, bool>;

### Description

not_equal_to is a binary function object. Its `operator()` returns `true` if `x` is not equal to `y`. You can pass a not_equal_to object to any algorithm that requires a binary function. For example, the transform algorithm applies a binary operation to corresponding values in two collections and stores the result. not_equal_to would be used in that algorithm in the following manner:

    vector<int> vec1;
    vector<int> vec2;
    vector<int> vecResult;
    .
    .
    .
    transform(vec1.begin(), vec1.end(),
              vec2.begin(),
              vecResult.begin(), not_equal_to<int>());

After this call to transform, `vecResult(n)` contains a `1` if `vec1(n)` was not equal to `vec2(n)` or a `0` if `vec1(n)` was equal to `vec2(n)`.

### Interface

    template <class T>
    struct not_equal_to : binary_function<T, T, bool> {
      bool operator() (const T&, const T&) const;
    };

### Warnings

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`.

### See Also

binary_function,Function Objects

Copyright (c) 1998, Rogue Wave Software, Inc.
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OEM Release, June 1998