sorting question

I have a class

class Point2D {

double x[2];

public:
....

}

I want to implement a function that can take in as input point2Dsort( double * pdA, int number_of_points) and sort it in lexicographic order. (i.e. if p1.x() > p2.x() then p1 > p2 ...

Is there a way to define operator< on the point class and implement point2Dsort using c++ sort() function?

Thanks,
--j