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
- Microsoft Visual C++ 5.0 Professional Edition
- Microsoft Visual C++ 6.0 Professional Edition
- Microsoft Visual C++ 6.0 Standard Edition
- Microsoft Visual C++ .NET 2002 Standard Edition
- Microsoft Visual C++ .NET 2003 Standard Edition
This article was previously published under Q158573
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.
SUMMARY
The following sample code illustrates how to use the set::key_comp and set::value_comp STL functions in Visual C++.
MORE INFORMATION
Required header
<set>
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.
//////////////////////////////////////////////////////////////////////
#pragma warning(disable:4786)
#include <set>
#include <iostream>
#if _MSC_VER > 1020 // if VC++ version is > 4.2
using namespace std; // std c++ libs implemented in std
#endif
typedef set<int,less<int>,allocator<int> > 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
REFERENCES
For the same topic about set::(key_, value_)comp, visit the following MSDN Web site: http://msdn.microsoft.com/library/en-us/vclang98/html/sample_setCC(key___value_)comp_(STL_Sample).asp?frame=true
Additional query words: STL STLSample value_comp key_comp
Keywords: kbhowto kbinfo kbtemplate kbstl kbcode kbfunctions KB158573
