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

#define STRING1          "A macro definition\n"
#define STRING2          "must be all on one line!\n"
#define EXPRESSION1      1 + 2 + 3 + 4
#define EXPRESSION2      EXPRESSION1 + 10
#define ABS(x)           (((x) < 0) ? -(x) : (x))
#define MAX(a,b)         ((a < b) ?  (b) : (a))
#define BIGGEST(a,b,c)   ((MAX(a,b) < c) ?  (c) : (MAX(a,b)))

int compare_doubles (const void *a, const void *b)
{
  const double *da = (const double *) a;
  const double *db = (const double *) b;

  if (*da > *db) {return 1;}
  else if (*da == *db) {return 0;}
  else {return -1;}
  //  return (*da > *db) - (*da < *db);
}



/*
int main ()
{
  printf (STRING1);
  printf (STRING2);
  printf ("%d\n", EXPRESSION1);
  printf ("%d\n", EXPRESSION2);
  printf ("%d\n", ABS(-5));
  printf ("Biggest of 1, 2, and 3 is %d\n", BIGGEST(1,2,3));
  
  int N = 3;
  double array[N];
  array[0] = 3.0;
  array[1] = 2.0;
  array[2] = 1.0;

  fprintf(stdout, "Before:\n");
  for (long i = 0; i < N; i++) {
    fprintf(stdout, "array[%d] = %f\n", i, array[i]);
  }

  qsort (array, N, sizeof (double), compare_doubles);

  fprintf(stdout, "After:\n");
  for (long i = 0; i < N; i++) {
    fprintf(stdout, "array[%d] = %f\n", i, array[i]);
  }
  return 0;
}
*/

//===========
#include <stdio.h>
// A normal function with an int parameter
// and void return type
void fun(int a)
{
  printf("Value of a is %d\n", a);
}

int main()
{
  // fun_ptr is a pointer to function fun()
  void (*fun_ptr)(int) = &fun;

  /* The above line is equivalent of following two
            void (*fun_ptr)(int);
	           fun_ptr = &fun;
  */

  // Invoking fun() using fun_ptr
  (*fun_ptr)(10);

  return 0;
}