#include <stdio.h>
#include <errno.h>

int show_a_double (double x) {

  printf(">> double: %09.15f\n", x);

}

int usage(char *progname) {

  char *str;

  printf("usage: %s <double-value>\n", progname);
  exit(ENOTSUP);

}

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

  double darg = 0.0;

  if (argc != 2) usage((char *const) argv[0]);
  else darg = atof(argv[1]);

  return darg;

}