a UCS-4 encoded string
the maximum length (number of characters) of @str to use. If @len < 0, then the string is nul-terminated.
location to store number of bytes read, or %NULL. If an error occurs then the index of the invalid input is stored here.
location to store number of #gunichar2 written, or %NULL. The value stored here does not include the trailing 0.
Return: a pointer to a newly allocated UTF-16 string. This value must be freed with g_free(). If an error occurs, %NULL will be returned and @error set.
GException on failure.
Convert a string from UCS-4 to UTF-16. A 0 character will be added to the result after the converted text.