@subheading stringprep
@anchor{stringprep}
@deftypefun {int} {stringprep} (char * @var{in}, size_t @var{maxlen}, Stringprep_profile_flags @var{flags}, const Stringprep_profile * @var{profile})
@var{in}: input/ouput array with string to prepare.

@var{maxlen}: maximum length of input/output array.

@var{flags}: a @code{Stringprep_profile_flags} value, or 0.

@var{profile}: pointer to @code{Stringprep_profile} to use.

Prepare the input zero terminated UTF-8 string according to the
stringprep profile, and write back the result to the input string.

Note that you must convert strings entered in the systems locale
into UTF-8 before using this function, see
@code{stringprep_locale_to_utf8()}.

Since the stringprep operation can expand the string, @code{maxlen}
indicate how large the buffer holding the string is.  This function
will not read or write to characters outside that size.

The @code{flags} are one of @code{Stringprep_profile_flags} values, or 0.

The @code{profile} contain the @code{Stringprep_profile} instructions to
perform.  Your application can define new profiles, possibly
re-using the generic stringprep tables that always will be part of
the library, or use one of the currently supported profiles.

@strong{Return value:} Returns @code{STRINGPREP_OK} iff successful, or an error code.
@end deftypefun