Area of a Polygon using cross product

polyArea.cpp

// https://www.youtube.com/watch?v=WAyPIMme3Yw&list=PL2_aWCzGMAwLL-mEB4ef20f3iqWMGWa25&index=8

#include <iostream>
#include <cmath>

struct Point {
    double x;
    double y;
    Point(double a, double b):
    x(a), y(b)
    {
    }
};

double crossProduct(Point a, Point b) {
    return a.x * b.y - a.y * b.y;
}

// POINTER TO ARRAY
double getArea(Point vertices[], int size) {
    double area = 0;
    for (int i = 0; i < size; i++) {
        Point currentPoint = vertices[i];
        Point nextPoint = vertices[(i + 1) % size];
        area += crossProduct(currentPoint, nextPoint) / 2.0;
    }
    return std::abs(area);
}

int main(int argc, const char * argv[]) {
    Point a(2, 3);
    Point b(3, 1);
    Point vertices[2] = { a, b };
    int size = sizeof(vertices) / sizeof(Point);

    std::cout << getArea(vertices, size) << std::endl;
    
    return 0;
}