Proper implementation of removing vector elements

Question

ALL,

It's continuation of this thread.

What I tried is to write following code:

struct Remover : public std::binary_function<CPlayer,void,bool>
{
public:
    bool operator()(const CPlayer &player) const
    {
        return player.IsNewPlayer();
    }
};

and call it this way:

players_pool->erase( std::remove_if( players_pool->begin(), players_pool->end(), std::bind2nd( Remover() ) ) );

but it gives me an error:

std::bind2nd(): expects 2 arguments - 1 provided.

How do I properly call this functor?

Thank you.

Do you understand the error message? `expects 2 arguments - 1 provided.` - Also, have you read the documentation of `std::bind2nd()`? — , Jul 14 '13 at 05:48
You need neither `bind2nd` nor `Remover`. Look at `std::mem_fun`. — n. m. could be an AI, Jul 14 '13 at 06:00
@n.m. note that `std::mem_fun` is deprecated. But [`std::mem_fn`](http://en.cppreference.com/w/cpp/utility/functional/mem_fn) could be an alternative. — juanchopanza, Jul 14 '13 at 07:22

Marcelo Cantos · Accepted Answer · 2013-07-14T06:03:57.190

You don't need to wrap Remover() in std::bind2nd().

Also, you don't need to derive from std::binary_function<> (which is wrong, anyway; Remover is a unary functor). You don't need to derive from anything, in fact.

Finally, if your compiler supports C++11, you can reduce your code down to this:

players_pool->erase( std::remove_if( begin(*players_pool), end(*players_pool),
                                     [](const CPlayer &player) {
                                         return player.IsNewPlayer();
                                     } ),
                     end(*players_pool) );

score 0 · Answer 2 · answered Jul 14 '13 at 05:56

0

Just change your binary_function to a unary_function.
You also need to add the end iterator to the erase call, in order to erase all removed values.

answered Jul 14 '13 at 05:56

Photon

3,182
1
15
16

Proper implementation of removing vector elements

2 Answers2