Strings and Opaque Data

Strings are written as opaque data, i.e. in their binary representation, therefore the result depends on the machines character set. Using just the basic characters a-z, A-Z, 0-9 should be save because their representation is identical in most character sets (they could cause trouble when a 16 bit character set is used), but language specific characters will lead to unexpected result.

To create machine-independent files (apart from strings) it is necessary to write all data with the appropriate XDR functions. For opaque data pointers like the char * data pointer in class Fe2d it is impossible to determine which XDR function has to be used, therefore such data can only be written in its machine-dependent binary representation. To avoid this problem the Fe2d data is only written if its size size_of_data is a multiple of sizeof(double). In this case data is expected to point an array of doubles and the data is written using xdr_double -- if data points to some other data type the resulting data will be machine-dependent.