Q156532: INFO: STL Sample for the remove_if Function
Article: Q156532
Product(s): Microsoft C Compiler
Version(s): 4.2,5.0,6.0
Operating System(s):
Keyword(s): kbcode kbVC420 kbVC500 kbVC600 kbDSupport
Last Modified: 27-MAR-2002
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The information in this article applies to:
- The Standard C++ Library, used with:
- Microsoft Visual C++, 32-bit Enterprise Edition, versions 4.2, 5.0, 6.0
- Microsoft Visual C++, 32-bit Professional Edition, versions 4.2, 5.0, 6.0
- Microsoft Visual C++, 32-bit Learning Edition, version 6.0
- Microsoft Visual C++.NET (2002)
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SUMMARY
=======
The sample code below illustrates how to use the remove_if, end, begin, and
bind2nd STL functions in Visual C++.
MORE INFORMATION
================
Required Header
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<algorithm>
Prototype
---------
template<class ForwardIterator, class Predicate> inline
ForwardIterator remove_if(ForwardIterator first,
ForwardIterator last,
Predicate pred)
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 remove_if algorithm removes all elements from the range (first, last) that
cause the predicate to return true. It returns an iterator equal to last - N,
where N = number of elements removed. The last N elements of the range have
undefined values. The size of the container remains the same.
Sample Code
-----------
NOTE: The first line in the sample code section is: // Compile options
needed: /GX
In VC++ .NET, /EHsc is set by default and is equivalent to /GX.
//////////////////////////////////////////////////////////////////////
//
// Compile options needed: /GX
//
// remove_if.cpp : Illustrates how to use the remove_if function.
//
// Functions:
//
// remove_if - remove all elements from the sequence that
// satisfies a predicate.
// bind2nd - Returns true for elements for which the condition is true
// begin - Returns an iterator that points to the first element in a
// sequence
// end - Returns an iterator that points one past the end of a sequence
//
// Written by Kalindi Sanghrajka
// of Microsoft Product Support Services,
// Software Core Developer Support.
// Copyright (c) 1996 Microsoft Corporation. All rights reserved.
//////////////////////////////////////////////////////////////////////
// disable warning C4786: symbol greater than 255 character,
// okay to ignore
#pragma warning(disable: 4786)
// disable warning C4244: possible loss of data,
// okay to ignore
#pragma warning(disable: 4244)
#include <iostream>
#include <vector>
#include <algorithm>
#include <functional>
#if _MSC_VER > 1020 // if VC++ version is > 4.2
using namespace std; // std c++ libs implemented in std
#endif
void main()
{
const int VECTOR_SIZE = 8 ;
// Define a template class vector of integers
typedef vector<int, allocator<int> > IntVector ;
//Define an iterator for template class vector of integer
typedef IntVector::iterator IntVectorIt ;
IntVector Numbers(VECTOR_SIZE) ; //vector containing numbers
IntVectorIt start, end, it, last;
start = Numbers.begin() ; // location of first
// element of Numbers
end = Numbers.end() ; // one past the location
// last element of Numbers
//Initialize vector Numbers
Numbers[0] = 10 ;
Numbers[1] = 20 ;
Numbers[2] = 10 ;
Numbers[3] = 15 ;
Numbers[4] = 12 ;
Numbers[5] = 7 ;
Numbers[6] = 9 ;
Numbers[7] = 10 ;
cout << "Before calling remove_if" << endl ;
// print content of Numbers
cout << "Numbers { " ;
for(it = start; it != end; it++)
cout << *it << " " ;
cout << " }\n" << endl ;
// remove all elements from Numbers that <= 10
last = remove_if(start, end, bind2nd(less_equal<int>(), 10) ) ;
cout << "After calling remove_if" << endl ;
// print content of Numbers
cout << "Numbers { " ;
for(it = start; it != end; it++)
cout << *it << " " ;
cout << " }\n" << endl ;
//print number of elements removed from Numbers
cout << "Total number of elements removed from Numbers = "
<< end - last << endl ;
//print only the valid elements of Number
cout << "Valid elements of Numbers { " ;
for(it = start; it != last; it++)
cout << *it << " " ;
cout << " }\n" << endl ;
}
Program output follows:
Before calling remove_if
Numbers { 10 20 10 15 12 7 9 10 }
After calling remove_if
Numbers { 20 15 12 15 12 7 9 10 }
Total number of elements removed from Numbers = 5
Valid elements of Numbers { 20 15 12 }
REFERENCES
==========
Visual C++, version 4.2, Visual C++ Books Online; click Visual C++ Books, C/C++,
and then Standard C++ Library Reference.
Additional query words: STL STLSample remove_if begin end bind2nd
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Keywords : kbcode kbVC420 kbVC500 kbVC600 kbDSupport
Technology : kbVCsearch kbAudDeveloper kbVCLibrary
Version : :4.2,5.0,6.0
Issue type : kbinfo
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