/* struct.c */

/* a slightly less silly C program, whose functionality however is
essentially identical to plainInts.c. The one significant difference is that
the program wraps the simple coordinate values in what C calls a "struct"
(cf. Pascal "record", etc.). "Struct" is C's provision for user-defined
data types--types relevant to the problem domain of a program, composed of
primitive C types and/or previously defined structs */

#include <stdio.h>

/* the syntax here is "struct { [list of component types and tags for
them] }"; in this case we're defined an unnamed type consisting of two
integers, and declared a (global) variable of the type called my_pt
struct {
  int x, y;
} my_pt;

void setPoint(int xVal, int yVal);

/* observe that the syntax for referring to components of structs is
[struct-variable].[member] */
int main() {
  my_pt.x = my_pt.y = 500;
  printf("After init my_pt.x is: %d, my_pt.y is: %d\n", my_pt.x, my_pt.y);
  setPoint(800, 1400);
  printf("After setPoint() my_pt.x is: %d, my_pt.y is: %d\n", my_pt.x, my_pt.y);
}

void setPoint(int xVal, int yVal) {
  my_pt.x = xVal;
  my_pt.y = yVal;
}