not_equal_to

Library:  General utilities

Does not inherit

• Local Index
• Summary
• Synopsis
• Description
• Interface
• See Also
• Standards Conformance

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

#include <functional>

namespace std {
  template <class T>
  struct not_equal_to;
}

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 find_if() algorithm finds the first occurrence of any value from one sequence in another sequence as determined by applying a binary comparision operation. not_equal_to would be used in that algorithm in the following manner:

vector<int> vec1;
vector<int> vec2;

vector<int>::iterator iter1;
.
.
.
iter1 = find_if(vec1.begin(), vec1.end(),
                vec2.begin(), vec2.end(), not_equal_to<int>());

After this call to find_if(), iter1 points to the first element in vec1 for which not_equal_to(vec1[n],vec2[n]) returned true, or, if there were no matches, iter1 points to vec2.end().

namespace std {

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

binary_function, Function Objects

ISO/IEC 14882:1998 -- International Standard for Information Systems -- Programming Language C++, Section 20.3.3