1

I have tried searching for this but couldn't really find a proper answer. I have a stl::set of a custom class I made.

The class looks like 

class myObject{

public:
  int a;
  int b;
  int c;

// constructor and operator < ()
}

The < comparison is based on b and c but I want to find elements in the set by a. Is there a way to do that other than performing a linear search by iterating over the set and checking for myObject.a? I am trying to get a sorted container of myObject but I need to be able to find elements in that container by the identifier a which is not really involved in the < comparison.

Okay, this is worded in a confusing way. Are you trying to change the stuff put into the views at runtime? If so, in the standard Activity, after your setContentView(...), you can do things like 

Button button = (Button)findViewById(R.id.reallyAwesomeSauceButton); 
button.setText("Click me!");

Just check out the Android documentation to see what you can do with a view at runtime. There's quite a bit

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1 に答える 1

2

boost::multi_index_container を使用してそれを行うことができます

class myObject
{
public:
    int a;
    int b;
    int c;
    bool operator < (const myObject& obj) const
    { return b < obj.b; }
};

using namespace boost::multi_index;
typedef multi_index_container<
    myObject,
    indexed_by<
        ordered_unique<identity<myObject> >, // index by operator <
        ordered_unique<member<myObject, int, &myObject::a> > // index by member a
  > 
> SetOfmyObjects;

typedef SetOfmyObjects::nth_index<0>::type SetIndex_b;
typedef SetOfmyObjects::nth_index<1>::type SetIndex_a;

...

    SetOfmyObjects s;
    const SetIndex_b& index_b = s.get<0>();
    SetIndex_b::iterator it_b;
    for (it_b = index_b.begin(); it_b != index_b.end(); ++it_b)
        // ordered by b
    const SetIndex_a& index_a = s.get<1>();
    SetIndex_a::iterator it_a;
    for (it_a = index_a.begin(); it_a != index_a.end(); ++it_a)
        // ordered by a
于 2012-11-02T20:21:59.313 に答える