/*
  The prototype for qsort is
     
  void qsort(void * base, size_t nmemb, size_t size,
             int (* compar)(const void *, const void *));

  it's in stdlib.h
  remember that size_t is just unsigned int
*/
/////////////////////////////////////////////////////////////

// to sort an array of ints

int compint(const void *a, const void *b)
{ int aa = *(int *)a, bb = *(int *)b;
  return aa - bb; }

  qsort(ints, n, sizeof(int), compint);

/////////////////////////////////////////////////////////////

// to sort a string character by character

int compchar(const void *a, const void *b)
{ int aa = *(char *)a, bb = *(char *)b;
  return aa - bb; }

  qsort(chars, n, sizeof(char), compchar);

/////////////////////////////////////////////////////////////

// to sort an array of char * strings

int compstr(const void *a, const void *b)
{ const char *aa = *(const char **)a;
  const char *bb = *(const char **)b;
  return strcmp(aa, bb); }

  qsort(strings, n, sizeof(char *), compstr);

/////////////////////////////////////////////////////////////

// to sort an array char[][size] of strings

int compstr(const void *a, const void *b)
{ return strcmp((const char *)a, (const char *)b); }

  qsort(strings, n, size, compstr);

/////////////////////////////////////////////////////////////

// to sort an array of structs

struct entry
{ char word[8];
  int blug, blag, bleg; };

entry array[111];

int compent(const void *a, const void *b)
{ entry *aa = (entry *)a;
  entry *bb = (entry *)b;
  return strcmp(aa->word, bb->word); }

  qsort(array, 111, sizeof(entry), compent);

/////////////////////////////////////////////////////////////

// to sort an array of pointers to structs

struct book
{ char *title;
  char *author; };

book *collection[100000];

int compbook(const void *a, const void *b)
{ book **aa = (book **)a;
  book **bb = (book **)b;
  book *aaa = *aa, *bbb = *bb;
  int r = strcmp(aaa->author, bbb->author);
  if (r != 0)
    return r;
  return strcmp(aaa->title, bbb->title); }

/////////////////////////////////////////////////////////////