void *bsearch(const void *key
const void *base
, size_t size
)(const void *, const
Performs a binary search. The beginning of the array is pointed
to by base. It searches for an element equal to that
pointed to by key. The array is nitems long with
each element in the array size bytes long.
The method of comparing is specified by the compar
function. This function takes two arguments, the first is the
key pointer and the second is the current element in the array
being compared. This function must return less than zero if the
compared value is less than the specified key. It must return
zero if the compared value is equal to the specified key. It
must return greater than zero if the compared value is greater
than the specified key.
The array must be arranged so that elements that compare less
than key are first, elements that equal key are next, and
elements that are greater than key are last.
If a match is found, a pointer to this match is returned.
Otherwise a null pointer is returned. If multiple matching keys
are found, which key is returned is unspecified