Inputing a File of 2d points and then sorting

I have a program that will take in 2d points and then compare the points. Example in the code

struct Point2D p1 = {1,2};
struct Point2D p2 = {1,2};

if (lessThan(&p1, &p2)) {
       puts("one point is less than the other");
   }
   else {
    puts("Equal");
   }

This code is working great.  But what I need is to take a file of points.  
Example:
1,2
1,4
1,3
2,4
1,6
2,6
3,1

As the file is parsed the values are ran through the  lesThan function.  
When the file is finsihed the values are in order from the smalles to the largest.

Example  
1,2
1,3
1,4
1,6
2,4
2,6
3,1


I am very rusty with C so I am not sure how I would do this.  I can parse a file of chars or strings, but not sure how to handle struct point values.

struct Point2D {
   int x;
   int y;
};
 
 int comparePoint2D ( struct Point2D *p1, struct Point2D *p2) {
   int result = p1->x == p2->x && p1->y == p2->y;
   return result;
}
 
int lessThan(const struct Point2D *p1, const struct Point2D *p2) {
   int result = (p1->x < p2->x) || (p1->x == p2->x && p1->y < p2->y);
   return result;   
} 
 
 
 
int main (void) {
   struct Point2D p1 = {1,2};
   struct Point2D p2 = {1,2};
  
   if (comparePoint2D(&p1, &p2)) {
       puts("Points are equal");
   } 
   else {
    puts("Points are not equal");
   }
   
   if (lessThan(&p1, &p2)) {
       puts("one point is less than the other");
   } 
   else {
    puts("Equal");
   }
   return 0;
}

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