Microsoft KB Archive/158573

= How to use the set::key_comp and set::value_comp Standard Template Library (STL) functions in Visual C++ =

Article ID: 158573

Article Last Modified on 7/15/2005

-

APPLIES TO

 The Standard C++ Library, when used with:  Microsoft Visual C++ 4.2 Enterprise Edition

 Microsoft Visual C++ 5.0 Enterprise Edition

 Microsoft Visual C++ 6.0 Enterprise Edition

 Microsoft Visual C++ 4.2 Professional Edition</li></ul>

 Microsoft Visual C++ 5.0 Professional Edition</li></ul>

 Microsoft Visual C++ 6.0 Professional Edition</li></ul>

 Microsoft Visual C++ 6.0 Standard Edition</li></ul>

 Microsoft Visual C++ .NET 2002 Standard Edition</li></ul>

 Microsoft Visual C++ .NET 2003 Standard Edition</li></ul> </li></ul>

-

<div class="notice_section">

This article was previously published under Q158573

<div class="notice_section">

<div class="notice_section">

Note Microsoft Visual C++ NET (2002) supported both the managed code model that is provided by the .NET Framework and the unmanaged native Windows code model. The information in this article applies to unmanaged Visual C++ code only.

<div class="summary_section">

SUMMARY
The following sample code illustrates how to use the set::key_comp and set::value_comp STL functions in Visual C++.

<div class="moreinformation_section">

Prototype
template<class _K, class _Pr, class _A> class set { public: // Function 1:

key_compare key_comp const;

// Function 2: value_compare value_comp const; } 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 key_comp function returns the stored function object that determines the order of elements in the controlled sequence. The value_comp function returns the same function that key_comp returns.

Sample code
////////////////////////////////////////////////////////////////////// // // Compile options needed: -GX // // SetComp.cpp: //     Illustrates how to use the key_comp function to obtain a //      function pointer that is the stored function object that //     determines the order of elements in the controlled sequence. //     It also illustrates how to use the value_comp function to //      obtain a function pointer that is the stored function object //     that determines the order of the elements in the controlled //     sequence (same as key_comp result). // // Functions: // //   key_comp     Returns a function pointer to the function that //                determines the order of elements in the controlled //                sequence. //   value_comp   Returns a function pointer to the function that //                determines the order of elements in the controlled //                sequence (same as key_comp). // // Written by Derek Jamison // of Microsoft Technical Support, // Copyright (c) 1996 Microsoft Corporation. All rights reserved. //////////////////////////////////////////////////////////////////////


 * 1) pragma warning(disable:4786)


 * 1) include
 * 2) include

using namespace std; // std c++ libs implemented in std #endif
 * 1) if _MSC_VER > 1020  // if VC++ version is > 4.2

typedef set<int,less ,allocator > SET_INT;

void truefalse(int x)

{ cout << (x?"True":"False") << endl; }

void main {

SET_INT s1;

cout << "s1.key_comp(8,10) returned "; truefalse(s1.key_comp(8,10)); // True

cout << "s1.value_comp(8,10) returned "; truefalse(s1.value_comp(8,10)); // True

cout << "s1.key_comp(10,8) returned "; truefalse(s1.key_comp(10,8)); // False

cout << "s1.value_comp(10,8) returned "; truefalse(s1.value_comp(10,8)); // False

cout << "s1.key_comp(8,8) returned "; truefalse(s1.key_comp(8,8)); // False

cout << "s1.value_comp(8,8) returned "; truefalse(s1.value_comp(8,8));  // False }

Program output
s1.key_comp(8,10) returned True s1.value_comp(8,10) returned True s1.key_comp(10,8) returned False s1.value_comp(10,8) returned False s1.key_comp(8,8) returned False s1.value_comp(8,8) returned False

<div class="references_section">