equal_to

     Function Object

Binary function object that returns true if its first argument equals its second

Contents

• Synopsis
• Description
• Interface
• See Also

#include <functional>

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 transform algorithm applies a binary operation to corresponding values in two collections and stores the result. 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(), 
          equal_to<int>());

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

template <class T>

    struct equal_to : binary_function<T, T, bool> 
{
   typedef typename binary_function<T, T, bool>::second_argument_type 
     second_argument_type;
   typedef typename binary_function<T, T, bool>::first_argument_type 
     first_argument_type;
   typedef typename binary_function<T, T, bool>::result_type 
     result_type;
   bool operator() (const T&, const T&) const;
};

binary_function, Function Objects