Function wiredtiger_struct_size 

pub unsafe extern "C" fn wiredtiger_struct_size(
    session: *mut WT_SESSION,
    lenp: *mut usize,
    format: *const c_char,
    ...
) -> c_int

Calculate the size required to pack a structure.

Note that for variable-sized fields including variable-sized strings and integers, the calculated sized merely reflects the expected sizes specified in the format string itself.

@snippet ex_all.c Get the packed size

@param session the session handle @param lenp a location where the number of bytes needed for the matching call to ::wiredtiger_struct_pack is returned @param format the data format, see @ref packing @errors