remove

Article
04/22/2008

Eliminates a specified value from a given range without disturbing the order of the remaining elements and returning the end of a new range free of the specified value.

template<class ForwardIterator, class Type>
   ForwardIterator remove(
      ForwardIterator _First, 
      ForwardIterator _Last, 
      const Type& _Val
   );

Parameters

_First
A forward iterator addressing the position of the first element in the range from which elements are being removed.
_Last
A forward iterator addressing the position one past the final element in the range from which elements are being removed.
_Val
The value that is to be removed from the range.

Return Value

A forward iterator addressing the new end position of the modified range, one past the final element of the remnant sequence free of the specified value.

Remarks

The range referenced must be valid; all pointers must be dereferenceable and within the sequence the last position is reachable from the first by incrementation.

The order of the elements not removed remains stable.

The operator== used to determine the equality between elements must impose an equivalence relation between its operands.

The complexity is linear; there are (_Last – _First) comparisons for equality.

The list class has a more efficient member function version of remove, which also relinks pointers.

Example

// alg_remove.cpp
// compile with: /EHsc
#include <vector>
#include <algorithm>
#include <iostream>

int main( ) {
   using namespace std;
   vector <int> v1;
   vector <int>::iterator Iter1, Iter2, new_end;

   int i;
   for ( i = 0 ; i <= 9 ; i++ )
      v1.push_back( i );

   int ii;
   for ( ii = 0 ; ii <= 3 ; ii++ )
      v1.push_back( 7 );
   
   random_shuffle ( v1.begin( ), v1.end( ) );
   cout << "Vector v1 is ( " ;
   for ( Iter1 = v1.begin( ) ; Iter1 != v1.end( ) ; Iter1++ )
      cout << *Iter1 << " ";
   cout << ")." << endl;

   // Remove elements with a value of 7
   new_end = remove ( v1.begin( ), v1.end( ), 7 );

   cout << "Vector v1 with value 7 removed is ( " ;
   for ( Iter1 = v1.begin( ) ; Iter1 != v1.end( ) ; Iter1++ )
      cout << *Iter1 << " ";
   cout << ")." << endl;

   // To change the sequence size, use erase
   v1.erase (new_end, v1.end( ) );

   cout << "Vector v1 resized with value 7 removed is ( " ;
   for ( Iter1 = v1.begin( ) ; Iter1 != v1.end( ) ; Iter1++ )
      cout << *Iter1 << " ";
   cout << ")." << endl;
}

Sample Output

Vector v1 is ( 7 1 9 2 0 7 7 3 4 6 8 5 7 7 ).
Vector v1 with value 7 removed is ( 1 9 2 0 3 4 6 8 5 6 8 5 7 7 ).
Vector v1 resized with value 7 removed is ( 1 9 2 0 3 4 6 8 5 ).

Requirements

Header: <algorithm>

Namespace: std

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