C++Talk.NET

jcteague@gmail.com · Guest

I have a class that has a set<int> member variable. the items in the
set are selected indices of a vector. I would like to sort the set on
the values in the vector they point too. Here is a part of the header
file:

Class A{
public:
int getX(int i) //basic getter. gets value from vector

private
set<int> selectedElements;
vector<int> x
};

I have tried several variations with a set comparison function with no
luck. Any help would be greatly appreciated.

thanks,
John

John Harrison · Guest

[email]jcteague (AT) gmail (DOT) com[/email] wrote:

John Harrison · Guest

Here's a cleaned up version of the above code

class A;

class Comp
{
public:
Comp(A* p) : ptr(p) {}
bool operator()(int a, int b) const;
private:
A* ptr;
};

class A
{
public:
A() : selectedElements(Comp(this)) {}
int getX(int i) { return x[i]; }
private:
set<int, Comp> selectedElements;
vector<int> x;
};

inline bool Comp::operator()(int a, int b) const
{
return ptr->getX(a) < ptr->getX(b);
}