Scandir ()

DESCRIPTION
The scandir() function scans the directory dir, calling
select() on each directory entry. Entries for which
select() returns non-zero are stored in strings allocated
via malloc(), sorted using qsort() with the comparison
function compar(), and collected in array namelist which
is allocated via malloc(). If select is NULL, all entries
are selected.

The alphasort() function can be used as the comparison
function for the scandir() function to sort the directory
entries into alphabetical order. Its parameters are the
two directory entries, a and b, to compare.

RETURN VALUE
The scandir() function returns the number of directory
entries selected or -1 if an error occurs.

The alphasort() function returns an integer less than,
equal to, or greater than zero if the first argument is
considered to be respecscandirtively less than, equal to, or
greater than the second.


How does the alphasort work in scandir?

From what I can tell it a pointer to a built in function. The function itself may look something similar to the cmpstringp function shown as an example on the qsort manpage: http://linux.die.net/man/3/qsort