Q158231: STL Sample for the binary_function Structure

Article: Q158231
Product(s): Microsoft C Compiler
Version(s): winnt:4.2
Operating System(s): 
Keyword(s): _IK
Last Modified: 06-MAY-2001

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The information in this article applies to:

- The Standard C++ Library 
- Microsoft Visual C++, 32-bit Enterprise Edition, version 4.2 
- Microsoft Visual C++, 32-bit Professional Edition, version 4.2 
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SUMMARY
=======

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

MORE INFORMATION
================

Required Header
---------------

     <functional>

Prototype
---------

     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 may 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.
  // 
  // Written by Mark Hagen
  // of Microsoft Product Support Services,
  // Copyright (c) 1996 Microsoft Corporation.
  // All rights reserved.
  //////////////////////////////////////////// 

  #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

REFERENCES
==========

Visual C++ Books On Line: Visual C++ Books:C/C++:Standard C++ Library Reference.

Additional query words: STL Sample binary_function

======================================================================
Keywords          : _IK 
Technology        : kbVCsearch kbAudDeveloper kbVC420 kbVC32bitSearch kbVCLibrary
Version           : winnt:4.2
Issue type        : kbhowto

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