Lab 2 : Calculate circumference and area of a circle (function)

int dia;
float area;
int rad;
float cir;
void setup() {
  size(300, 300);
  background(255);
  //setting variable
  dia=50;     //diameter
  //calculate
  rad=dia/2;
  area=3.14*rad*rad;
  cir=3.14*dia;
  //function call
  calculate_circle(5, 20);
}
  void calculate_circle(int x, int y) {
  //result
  fill(0);
  textSize(20);
  text("Diameter : "+dia, x, y);
  text("Area : "+area, x, y+30);
  text("Circumference : "+cir, x, y+60);
}