a UCS-4 encoded string
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.
a pointer to a newly allocated UTF-16 string. This value must be freed with glib.global.gfree. If an error occurs, null will be returned and error set.
Convert a string from UCS-4 to UTF-16. A 0 character will be added to the result after the converted text.