centroid of a triangle

/*
-std=c99 -Wall -Wextra -Wpedantic -Wshadow
centroid of a triangle
*/

#include <stdio.h>
#include <stdlib.h>

typedef struct{
    double x;
    double y;
}Point2D;

Point2D CentroidOfTriangle( Point2D a, Point2D b, Point2D c )
{
    //Point2D ret;
    //ret.x = (a.x + b.x + c.x) / 3.0;
    //ret.y = (a.y + b.y + c.y) / 3.0;
    //return ret;

    return (Point2D) { (a.x + b.x + c.x) / 3.0, (a.y + b.y + c.y) / 3.0 };

}


int main()
{

    Point2D p1, p2, p3, ret_v;

    p1.x = 0.0;
    p1.y = 0.0;

    p2.x = 10.0;
    p2.y = 0.0;

    p3.x = 10.0;
    p3.y = 10.0;

    ret_v = CentroidOfTriangle( p1, p2, p3 );

    printf("(1) p1: %f %f p2: %f %f p3: %f %f centroid: %f %f\n",
            p1.x, p1.y, p2.x, p2.y, p3.x, p3.y, ret_v.x, ret_v.y );



    p1.x = 71.0;
    p1.y = 8.0;

    p2.x = 30.0;
    p2.y = 24.0;

    p3.x = 67.0;
    p3.y = 51.0;

    ret_v = CentroidOfTriangle( p1, p2, p3 );

    printf("(2) p1: %f %f p2: %f %f p3: %f %f centroid: %f %f\n",
            p1.x, p1.y, p2.x, p2.y, p3.x, p3.y, ret_v.x, ret_v.y );


    p1.x = 7.1;
    p1.y = 0.8;

    p2.x = 3.0;
    p2.y = 2.4;

    p3.x = 6.7;
    p3.y = 5.1;

    ret_v = CentroidOfTriangle( p1, p2, p3 );

    printf("(3) p1: %f %f p2: %f %f p3: %f %f centroid: %f %f\n",
            p1.x, p1.y, p2.x, p2.y, p3.x, p3.y, ret_v.x, ret_v.y );



    p1.x = 0.71;
    p1.y = 0.08;

    p2.x = 0.3;
    p2.y = 0.24;

    p3.x = 0.67;
    p3.y = 0.51;

    ret_v = CentroidOfTriangle( p1, p2, p3 );

    printf("(4) p1: %f %f p2: %f %f p3: %f %f centroid: %f %f\n",
            p1.x, p1.y, p2.x, p2.y, p3.x, p3.y, ret_v.x, ret_v.y );


    return 0;
}

/*
output:

(1) p1: 0.000000 0.000000 p2: 10.000000 0.000000 p3: 10.000000 10.000000 centroid: 6.666667 3.333333
(2) p1: 71.000000 8.000000 p2: 30.000000 24.000000 p3: 67.000000 51.000000 centroid: 56.000000 27.666667
(3) p1: 7.100000 0.800000 p2: 3.000000 2.400000 p3: 6.700000 5.100000 centroid: 5.600000 2.766667
(4) p1: 0.710000 0.080000 p2: 0.300000 0.240000 p3: 0.670000 0.510000 centroid: 0.560000 0.276667

*/