lexicographical sorting

[tim.lino]

Dear all,

I would like to sort the elements in a vector in a lexicographical
order. The elements are defined as:

class E
{
public:
int x;
int y;
}

where x is the first rank and y is the second rank in the
lexicographical order. Suppose I have vector<E>, how I can sort E in a
lexicographical order? Is it any built-in function to do that?

Thank you.

[Kai-Uwe Bux]

ti******@gmail.com wrote:

I would like to sort the elements in a vector in a lexicographical
order. The elements are defined as:

class E
{
public:
int x;
int y;
}

where x is the first rank and y is the second rank in the
lexicographical order. Suppose I have vector<E>, how I can sort E in a
lexicographical order? Is it any built-in function to do that?

You need to (a) overload operator< for the type E or (b) specialize
std::less<for the type E. Then, std::sort() will just sort any range for
you.

Alternatively, you could ditch the class E and just use std::pair<int,int>
instead. Then, the appropriate overload for operator< would be defined
already (and, yes, it does lexicographic order).
Best

Kai-Uwe Bux