Answer T22

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

/* declare the Point type */
typedef struct
{
  int x, y;
} Point;

/* function to print a Point */
void printPoint( Point *p )
{
  printf("(%d, %d)\n", p->x, p->y );
}

int main()
{
  /* declare a Point and allocate memory */
  Point *point = (Point *)malloc( sizeof( Point ) );

  /* don't change these statements */
  point->x = -23;
  point->y = 45;

  /* print values */
  printPoint(  point  );

  /* free memory */
  free( point );
  
  return 0;
}

Notice how this works:

  printPoint(  point  );

The pointer variable point contains the address of the struct. It is this address that needs to be passed to the function. Call-by-value does exactly that.

Sometimes students think that when a function parameter is an address that the function call must use an & ampersand:

  printPoint(  &point  );

But this would pass the address of the variable point, not the address of the struct.