equal_to

Module:  Standard C++ Library   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 equals its second

#include <functional>

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

equal_to is a binary function object. Its operator() returns true if x is equal to y. You can pass an 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 comparison operation. 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(), equal_to<int>());

After this call to find_if(), iter1 points to the first element in vec1 for which 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 equal_to : binary_function<T, T, bool> { 
    bool operator()(const T& x, const T& y) const;
  }; 
}

binary_function, Function Objects

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

Copyright (c) 1994-2006 Rogue Wave Software, a Quovadx Division.
Licensed under the Apache License, Version 2.0.
Contact Rogue Wave about documentation or support issues. You can also seek help from other developers through the Apache stdcxx community (see below).