C++/List/list remove
Good way and bad way to remove elements in a list
<source lang="cpp">
/* The following code example is taken from the book
* "The C++ Standard Library - A Tutorial and Reference" * by Nicolai M. Josuttis, Addison-Wesley, 1999 * * (C) Copyright Nicolai M. Josuttis 1999. * Permission to copy, use, modify, sell and distribute this software * is granted provided this copyright notice appears in all copies. * This software is provided "as is" without express or implied * warranty, and with no claim as to its suitability for any purpose. */
- include <iostream>
- include <list>
- include <algorithm>
using namespace std; int main() {
list<int> coll; // insert elements from 6 to 1 and 1 to 6 for (int i=1; i<=6; ++i) { coll.push_front(i); coll.push_back(i); } // remove all elements with value 3 // - poor performance coll.erase (remove(coll.begin(),coll.end(), 3), coll.end()); // remove all elements with value 4 // - good performance coll.remove (4);
}
</source>
Remove all elements with the same value
<source lang="cpp">
- include <iostream>
using std::cout; using std::endl;
- include <list> // list class-template definition
- include <algorithm> // copy algorithm
- include <iterator> // ostream_iterator
int main() {
int array[ 4 ] = { 2, 6, 4, 8 }; std::list< int > values; // create list of ints std::list< int > otherValues; // create list of ints std::ostream_iterator< int > output( cout, " " ); // insert items in values values.push_front( 1 ); values.push_front( 3 ); values.push_back( 4 ); values.push_back( 1 ); values.push_back( 2 ); values.push_back( 3 ); cout << "values contains: "; std::copy( values.begin(), values.end(), output ); values.remove( 1 ); // remove all 1s cout << "\n\nvalues contains: "; std::copy( values.begin(), values.end(), output ); cout << endl; return 0;
}
/*
values contains: 3 1 4 1 2 3 values contains: 3 4 2 3
*/ </source>