Illustrate the difference between char *, char [], char *[], etc., in C.

charpointer.c

#include <stdio.h>
#include <string.h>

/* z is format specifier for size_t, the return type of sizeof */
#define SIZEFMT "\t%zu\t%s\n"

/* sizeof gives the memory compiler allocates for x.
   # is the stringify operator in the C preprocessor.
   for example, #token -> "token". */
#define printsize(x) printf(SIZEFMT, sizeof(x), #x)

#define printlenstr(s) printf(SIZEFMT, strlen(s), (s))

#define printline() printf("\n")

int main(void)
{
  /* with array/string literals at initialization,
     the sizes are technically unnecessary
     -- they're given for illustrative purposes */
  char *ap[5] = {"alpha", "beta", "gamma", "delta", "epsilon"};
  char aa[3][4] = {"foo", "bar", "baz"};
  char **pp = &ap[0];
  char (*pa)[4] = &aa[0];
  char a[] = "hello, world";
  char *p = "hello";

  int i, size;

  printsize(char);  /* according to the C standard this is always 1 */
  printline();

  printsize(char *);  /* size of char pointer --> 4 on 32-bit machine,
                         8 on 64-bit machine */
  printsize(p);  /* == sizeof(char *) */
  printlenstr(p);
  printline();

  printsize(char [13]);
  printsize(a);  /* == (strlen(a) + 1) * sizeof(char) -- +1 for ending '\0'. */
  printlenstr(a);
  printline();

  printsize(char [3][4]);
  printsize(aa);  /* == 3 * 4 * sizeof(char) */
  size = (int)(sizeof(aa) / sizeof(aa[0]));
  for (i = 0; i < size; i++)
    printlenstr(aa[i]);
  printline();

  printsize(char (*)[3]);
  printsize(pa);  /* == sizeof(char (*)[N]) == sizeof(char **) */
  for (i = 0; i < 3; i++)
    printlenstr(pa[i]);
  printline();

  printsize(char *[5]);
  printsize(ap);  /* == sizeof(char *) * 5 */
  size = (int)(sizeof(ap) / sizeof(ap[0]));
  for (i = 0; i < size; i++)
    printlenstr(ap[i]);
  printline();

  printsize(char **);
  printsize(pp);  /* == sizeof(char **) */
  for (i = 0; i < 5; i++)
    printlenstr(pp[i]);
  printline();

  return 0;
}

Nice illustration ! Thanks.