get a member of each element in an STL container

[Christopher Pisz]

Is there a way to build a seperate array of objects, when those objects are
members of other objects, which are contained in a STL data structure?
, without iterating through the whole list one by one and getting them
seperatlely.


class A
{
public:
int * m_data;
};

typdef list<A> MyList;
MyList g_mylist;

void Foo()
{
// for each A object I need the data member
int ** datalist = ??
}

 

[Victor Bazarov]

Is there a way to build a seperate array of objects, when those
objects are members of other objects, which are contained in a STL
data structure? , without iterating through the whole list one by one
and getting them seperatlely.


class A
{
public:
int * m_data;
};

typdef list<A> MyList;
MyList g_mylist;

void Foo()
{
// for each A object I need the data member
int ** datalist = ??
}

No, there is no way to do that without iterating through the whole
list. However, you could avoid iterating yourself if you write
a particular _functor_ and then use 'std::for_each'. Of course it
only means you're hiding the actual iteration behind the call to
'for_each' (and internally it does iterate through the range of
iterators you pass in), but it might be what you're asking about.

V