binary_function Structure (STL Sample)

The sample code below illustrates how to use the binary_function structure in Visual C++.

Required Header:
< functional >

template<class _A1, class _A2, class _R>
     struct binary_function
     {
         typedef _A1 first_argument_type;
         typedef _A2 second_argument_type;
         typedef _R result_type;
     };

Note: The class/parameter names in the prototype do not match the version in the header file. Some have been modified to improve readability.

Description:
The binary_function<A,B,C> class is used as a base class to allow the user to easily define binary operator functions that take data types A and B as arguments and return data type C objects.

Sample Code:

////////////////////////////////////////////
//
// Compile options needed: /GX
//
// binfunc.cpp : Illustrating the binary_function
//               structure.
//
// Structure used: binary_function<A,B,C> - base
//                 class used to create operator
//                 functions taking data types A
//                 and B and returning data type C.
////////////////////////////////////////////

#include <functional>
#include <iostream>

using namespace std ;

class binary_test : public binary_function<binary_test &,int,float>
{
public:
  float value;
  binary_test(){value=10.0;}
  binary_test(float x){value=x;}
  result_type operator<<(second_argument_type arg2);
};

binary_test::result_type
binary_test::operator<<(binary_test::second_argument_type arg2)
{
  value = ((int)value) << arg2;
  cout << "New value after shift is" << value << endl;
  return value;
}

void main(void)
{
  binary_test item;

  cout << "Begin" << endl;
  item = item << 2;
}

 

Program Output is:

Begin
New value after shift is 40.0