Thread: Unsigned long long to something longer

Code:

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

#define LONGLONGSIZE (sizeof (unsigned long long))

union intstr {
  unsigned long long ikey;
  char               skey[LONGLONGSIZE];
};

unsigned hashShortString (char v[], unsigned M)
{ 
  union intstr *is;

  is = (union intstr *) v;

  return is->ikey &#37; M;
}

int main (int argc, char *argv[])
{
  char key[LONGLONGSIZE];

  if (2 != argc) {
    printf ("USAGE: hash_short STRING\n");
    printf ("  (STRING will be truncated after %u characters)\n", 
            LONGLONGSIZE *LONGSIZE);
    return EXIT_FAILURE;
  }
  strncpy (key, argv[1], LONGLONGSIZE * LONGSIZE);
  printf ("Hash: %u\n", hashShortString (key, 8191));

  return EXIT_SUCCESS;
}

This is my lecturer's code for hashing short strings, I'm not entirely sure why this can't take more than 8 characters, I'm guessing because it's in integer form? Any hints?

The stuff in red is what I tried doing, it says the string will terminate after 64 characters but gives a segfault after I enter something in.