Paul A Bristow said: (by the date of Wed, 15 Mar 2006 15:23:50 -0000)
| > | This suggests that it is a broken feature of Microsoft's | > | operator>> for doubles read from filestreams. | | | why not just read the string, ans use boost::lexical_cast<double> ? | | -- | Janek Kozicki
I fear that lexical_cast uses the same method of reading from a stringstream :-((
And that our testing of lexical_cast is insufficient to catch it.
Some very rough tests of lexical_cast suggest that several percent of not very random double values fail to loopback ( 1 bit wrong), but I don't have time to work on this at present.
but if during saving lexical_cast<string>(some_double_value) is used IMHO no data should be lost at all. operator<< for string cannot make a mistake. Also operator>> for string shouldn't make a mistake, otherwise copying around textual data with << and >> should lead to data corruption. (think copying text file using microsoft's operators << and >> ) bear in mind that lexical_cast<string>(foo) converts double to string without any data loss (that's the exact purpose of lexical_cast). Then later if this data is treated as string then it's not possible to loss any information (otherwise we have a plain corruption of textual data). so during save you convert double to string, then save. when you load it - you load a string, then convert it to double. operator>> is not converting anything, it just works with strings. -- Janek Kozicki |