c++ list sorting

[mehmetned]

I have a class A and it has x,y and z integer attributes I have created a list sequence container which has a type A list alist I want to sort the elements in this list according to y value. How can i do that? alist.sort() only sorts the elements according to the first attribute defined in the constructor.

[Stephen Hewitt]

You have a number of options. The first is to define an operator < for your class:

bool operator<(const A &lhs, const A &rhs)
{
return lhs.y < rhs.y;
}

You would make it a friend of class A if it needs access to private members of the class. Another option is to define a predicate function and pass it to the std::list<...>::sort function. This option would enable you to have multiple sort orders. Example:

class A
{
// ...Stuff missing...
public:
static bool SortByYPred(const A &lhs, const A &rhs)
{
return lhs.y < rhs.y;
}
// ...Stuff missing...
};

Now call std::list<...>::sort like this:

alist.sort(&A::SortByYPred);

mehmetned wrote:

alist.sort() only sorts the elements according to the first attribute defined in the constructor.

The constructor has nothing to do with sort order.

Steve