qsort - sorts an array
void qsort(void *base, size_t nmemb, size_t size
int (*compar))(const void *, const void *))
The qsort() function sorts an array with nmemb elements of
size size. The base argument points to the start of the
The contents of the array are sorted in ascending order
according to a comparison function pointed to by compar,
which is called with two arguments that point to the objects
The comparison function must return an integer less than,
equal to, or greater than zero if the first argument is con-
sidered to be respectively less than, equal to, or greater
than the second. If two members compare as equal, their
order in the sorted array is undefined.
The qsort() function returns no value.
SVID 3, POSIX, BSD 4.3, ISO 9899