Q158572: STL Sample set::(lower_, upper_)bound, equal_range Functions
Article: Q158572
Product(s): Microsoft C Compiler
Version(s): winnt:4.2,5.0,6.0
Operating System(s):
Keyword(s): _IK kbVC420 kbVC500 kbVC600 kbDSupport
Last Modified: 05-MAY-2001
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The information in this article applies to:
- The Standard C++ Library, used with:
- Microsoft Visual C++, 32-bit Enterprise Edition, version 4.2
- Microsoft Visual C++, 32-bit Professional Edition, version 4.2
- Microsoft Visual C++, 32-bit Enterprise Edition, version 5.0
- Microsoft Visual C++, 32-bit Professional Edition, version 5.0
- Microsoft Visual C++, 32-bit Enterprise Edition, version 6.0
- Microsoft Visual C++, 32-bit Professional Edition, version 6.0
- Microsoft Visual C++, 32-bit Learning Edition, version 6.0
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SUMMARY
=======
The following sample code illustrates how to use the set::lower_bound,
set::upper_bound, and set::equal_range STL functions in Visual C++.
MORE INFORMATION
================
Required Header
---------------
<set>
Prototype
---------
template<class _K, class _Pr, class _A>
class set {
public:
// Function 1:
const_iterator lower_bound(const _K& _Kv) const;
// Function 2:
const_iterator upper_bound(const _K& _Kv) const;
// Function 3:
_Paircc equal_range(const _K& _Kv) 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 lower_bound function returns an iterator to the earliest element in the
controlled sequence that has a key that does not match the value passed to the
lower_bound function. The upper_bound function returns an iterator to the
earliest element in the controlled sequence that has a key that matches the
value passed to the upper_bound function. If no such element exists, the
function returns end(). In both cases, the function set::key_comp()(key, x) is
used to determine if the keys match. The equal_range function returns a pair
value, where .first is the result of the lower_bound function, and .second is
the result of the upper_bound function.
Sample Code
-----------
//////////////////////////////////////////////////////////////////////
//
// Compile options needed: -GX
//
// SetBoundRange.cpp:
// Illustrates how to use the lower_bound function to get an
// iterator to the earliest element in the controlled sequence
// that has a key that does not match the value passed to the
// function. It also illustrates how to use the upper_bound
// function to get an iterator to the earliest element in the
// controlled sequence that has a key that matches the value
// passed to the function. The last thing it illustrates is
// how to use the equal_range function to get a pair value that
// contains the lower_bound and upper_bound results of the key.
//
// Functions:
//
// lower_bound Returns an iterator whose value does not match the
// key passed to the function, or end() if no such
// element exists.
// upper_bound Returns an iterator whose value matches the key
// passed to the function, or end() if no such element
// exists.
// equal_range Returns a pair of (lower_bound,upper_bound).
//
// Written by Derek Jamison
// of Microsoft Technical Support,
// Copyright (c) 1996 Microsoft Corporation. All rights reserved.
//////////////////////////////////////////////////////////////////////
#pragma warning(disable:4786)
#include <set>
#include <iostream>
using namespace std;
#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 main() {
SET_INT s1;
SET_INT::iterator i;
cout << "s1.insert(5)" << endl;
s1.insert(5);
cout << "s1.insert(10)" << endl;
s1.insert(10);
cout << "s1.insert(15)" << endl;
s1.insert(15);
cout << "s1.insert(20)" << endl;
s1.insert(20);
cout << "s1.insert(25)" << endl;
s1.insert(25);
cout << "s1 -- starting at s1.lower_bound(12)" << endl;
// prints: 15,20,25
for (i=s1.lower_bound(12);i!=s1.end();i++)
cout << "s1 has " << *i << " in its set." << endl;
cout << "s1 -- starting at s1.lower_bound(15)" << endl;
// prints: 15,20,25
for (i=s1.lower_bound(15);i!=s1.end();i++)
cout << "s1 has " << *i << " in its set." << endl;
cout << "s1 -- starting at s1.upper_bound(12)" << endl;
// prints: 15,20,25
for (i=s1.upper_bound(12);i!=s1.end();i++)
cout << "s1 has " << *i << " in its set." << endl;
cout << "s1 -- starting at s1.upper_bound(15)" << endl;
// prints: 20,25
for (i=s1.upper_bound(15);i!=s1.end();i++)
cout << "s1 has " << *i << " in its set." << endl;
cout << "s1 -- s1.equal_range(12)" << endl;
// does not print anything
for (i=s1.equal_range(12).first;i!=s1.equal_range(12).second;i++)
cout << "s1 has " << *i << " in its set." << endl;
cout << "s1 -- s1.equal_range(15)" << endl;
// prints: 15
for (i=s1.equal_range(15).first;i!=s1.equal_range(15).second;i++)
cout << "s1 has " << *i << " in its set." << endl;
}
Program Output
--------------
s1.insert(5)
s1.insert(10)
s1.insert(15)
s1.insert(20)
s1.insert(25)
s1 -- starting at s1.low
s1 has 15 in its set.
s1 has 20 in its set.
s1 has 25 in its set.
s1 -- starting at s1.low
s1 has 15 in its set.
s1 has 20 in its set.
s1 has 25 in its set.
s1 -- starting at s1.upp
s1 has 15 in its set.
s1 has 20 in its set.
s1 has 25 in its set.
s1 -- starting at s1.upp
s1 has 20 in its set.
s1 has 25 in its set.
s1 -- s1.equal_range(12)
s1 -- s1.equal_range(15)
s1 has 15 in its set.
REFERENCES
==========
Visual C++ Books Online: Visual C++ Books; C/C++; Standard C++ Library Reference
Additional query words: STL STLSample equal_range lower_bound upper_bound string
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Keywords : _IK kbVC420 kbVC500 kbVC600 kbDSupport
Technology : kbVCsearch kbAudDeveloper kbVCLibrary
Version : winnt:4.2,5.0,6.0
Issue type : kbinfo
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