Boost logo

Boost :

From: Gary Powell (powellg_at_[hidden])
Date: 2002-02-20 20:18:47

The specific problem that got me thinking about this is that I
couldn't find an easy way to make a predicate compare only
the ".second" member of a pair, as in a map lookup by value:

    typedef std::map<int,float> map_t;

    // find the map entry whose value is 3.14
    void findpi(const map_t& themap)
        std::find_if(themap.begin(), themap.end(),
                     member_equal(&map_t::value_type::second, 3.14));

The LL solution is of course:

        std::find_if(themap.begin(), themap.end(),
                     ( _1->*second == 3.14) );


Boost list run by bdawes at, gregod at, cpdaniel at, john at