pointers.c

// compile with 
//   gcc pointers.c

#include <stdio.h>

typedef struct {
  int x;
  int y;
} point_t;

void printPointXY(int x, int y) {
  printf("The point is: {%d, %d}\n", x, y);
}

int main(int argc, char* argv[]) {

  // create a point
  point_t X = {10, 15};

  // create a pointer to that point!
  point_t* pX = &X;

  // there are a few (roughly equivalent) ways to access the point values through that pointer
  // 1. de-reference that shit into a point, then access as you would normally (with a .)
  // 2. de-reference in line with parentheses, then access as you would normally (with a .)
  // 3. stabby arrow of syntactic sugar (equivalent... but like... way cooler looking)

  // a couple of vars to read out the values of the point's x & y into
  int x, y;

  // 1.
    // de-reference the pointer into a normal point.
    point_t X2 = *pX;
    // then access the fields like a normal struct
    x = X2.x;
    y = X2.y;
    printPointXY(x,y);

  // 2.
    // de-refence the pointer in-line, and access the fields
    x = (*pX).x;
    y = (*pX).y;
    printPointXY(x,y);

  // 3.
    // syntactic sugar ( -> de-references the pointer, AND accesses the field)
    x = pX->x;
    y = pX->y;
    printPointXY(x,y);
}