I'm having problems with deserialising floating-point (double) values that are written to an XML file. I'm reading the values back in and comparing them to what I saved to ensure that my file has been written correctly. However, some of the values differ in about the seventeenth significant figure (or thereabouts). I thought Boost serialization used some numerical limit to make sure that values are serialised exactly to full precision, so what is happening here? Example: Value in original object, written to file: 0.0019075645054089487 Value actually stored in file (by examination of XML file): 0.0019075645054089487 [identical to value written to file] Value after deserialisation: 0.0019075645054089489 It looks like there is a difference in the least-significant bit, as examining the memory for these two values gives: Original value: b4 83 9b ca e7 40 5f 3f Deserialised value: b5 83 9b ca e7 40 5f 3f (where the least-significant byte is on the left) Note the difference in the first bytes. I'm using Boost 1.33.1 with Visual Studio 7.1.3088 in debug mode. Paul