Compare "const int", "#define", and "enum".

constant.c

#include <stdio.h>

/*
  constant.c - compare "const int", "#define", and "enum".
  inspired by:
  http://stackoverflow.com/questions/1674032/static-const-vs-define-in-c
 */

/* gcc constant.c -o constant */
/* gcc -std=c89 -pedantic -DOPTION_1 constant.c -o constant */
/* gcc -g -DOPTION_1 -DUSE_DEBUGGER constant.c -o constant */
/* gcc -DOPTION_2 constant.c -o constant */

#if defined(OPTION_1)
  static const int var = 5;
#elif defined(OPTION_2)
  #define var 5
#else
  enum { var = 5 };
#endif

void test_array(void)
{
  int array[var];
  int i;

  printf("**** test_array ****\n");
  for (i = 0; i < var; i++) {
    array[i] = i;
    printf("array[%d] = %d\n", i, array[i]);
  }
}

void test_switch(void)
{
#if !defined(OPTION_1) || !defined(USE_DEBUGGER)
  int i;

  printf("**** test_switch ****\n");
  for (i = 0; i < 7; i++) {
    switch (i) {
    case var:
      printf("i = %d\n", var);
      break;
    }
  }
#endif
}

int main(void)
{
  test_array();
  test_switch();

  return 0;
}