comparison - C# IComparable for X and Y co-ordinates -

suppose have list<point> stores list of x , y points, want these ordered. suppose not know domain of x , y values in advance, i'll use long large enough purposes.

at given moment, list can have large or small amount of points, , these points sparsely distributed, need able efficiently retrieve , insert particular points if exist in list.

in past, i've used icomparable<> , list.binarysearch() great success. unfortunately, need able insert , retrieve based on both x , y value.

if know domain of x , y in advance, , domain small enough, can add numbers 1 number raised next power of domain of other. ensures no collisions , can efficiently retrieve/insert values. example, if x , y both between 0 , 9, can compare on 10 * x + y. because data types 64-bit integers, can't this.

without restricting domain, there other way can achieve functionality?

one method work compare on x.tostring("n19") + y.tostring("n19"), string comparison instead of numerical comparison , come huge performance penalty.

edit: need "n19" because otherwise (x = 1234, y = 5) resolve same (x = 1, y = 2345); , other collisions in between.

instead of combining multiple components of vector 1 scalar value comparison compare each component, e.g.

int compareto(point p) {     if (this.x < p.x)     {         return -1;     }     else if (this.x > p.x)     {         return 1;     }     else     {         return this.y.compareto(p.y);     }         }