remove (STL Sample)

The sample code below illustrates how to use the remove STL function in Visual C++.

Required Header:
<algorithm>

template<class ForwardIterator, class Type> inline
     ForwardIterator remove(ForwardIterator first, ForwardIterator last, const T& value)

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 algorithm removes all elements that match value from the range (first, last). 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:

//////////////////////////////////////////////////////////////////////
//
// Compile options needed: /GX
//
// remove.cpp : Illustrates how to use the remove function.
//
// Functions:
//
//   remove - remove all elements from the sequence that match value.
//   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.
//////////////////////////////////////////////////////////////////////

// disable warning C4786: symbol greater than 255 character,
// okay to ignore
#pragma warning(disable: 4786)

#include <iostream>
#include <vector>
#include <algorithm>
#include <functional>

using namespace std;


void main()
{
    const int VECTOR_SIZE = 8 ;

    // Define a template class vector of integers
    typedef vector<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" << endl ;

    // print content of Numbers
    cout << "Numbers { " ;
    for(it = start; it != end; it++)
        cout << *it << " " ;
    cout << " }\n" << endl ;

    // remove all elements from Numbers that match 10
     last = remove(start, end, 10) ;

    cout << "After calling remove" << 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 is:

Before calling remove
Numbers { 10 20 10 15 12 7 9 10  }

After calling remove
Numbers { 20 15 12 7 9 7 9 10  }

Total number of elements removed from Numbers = 3
Valid elements of Numbers { 20 15 12 7 9  }