remove_if and vector

remove_if.cpp

// -*- compile-command: "clang++ -std=gnu++0x -stdlib=libc++ -o remove_if remove_if.cpp" -*-
#include <iostream>
#include <vector>

using std::cout;
using std::endl;

int main (int, char **) {
  std::vector<int> ints = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
  cout << "Range-based for loop:" << endl;
  cout << ints . size () << " elements in ints" << endl;
  // will remove
  for( auto &x : ints )
  {
    ints.erase( remove_if( ints.begin()
                          , ints.end()
                          , [=](const int y){ return x == y; } )
                , ints.end() );
    // And yet this will happen ten times!
    cout << x << endl;
  }
  cout << ints . size () << " elements in ints" << endl;

  ints = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
  cout << "Traditional iterator-based for loop:" << endl;
  cout << ints . size () << " elements in ints" << endl;
  for( auto x = ints.begin(); x < ints.end(); ++x )
  {
    ints.erase( remove_if( ints.begin()
                          , ints.end()
                          , [=](const int y){ return *x == y; } )
                , ints.end() );
    // And yet this will happen ten times!
    cout << *x << endl;
  }
  cout << ints . size () << " elements in ints" << endl;

  cout << "Range-based for loop on copy:" << endl;
  ints = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
  auto ints_copy = ints;
  for( auto x : ints_copy )
  {
    ints.erase( remove_if( ints.begin()
                          , ints.end()
                          , [=](const int y){ return x == y; } )
                , ints.end() );
    cout << x << endl;
  }
  cout << ints.size() << " elements in ints" << endl;
  return 0;
}