I am having a problem with a regex_match in Boost 1.33.0. Perhaps I am missing something; perhaps it is a bug that has been fixed. The pattern "[+-]?(\\d+(\\.\\d*)?|\\.\\d+)([Ee][+-]?\\d+)?" should match only floating-point numbers that can be read by sscanf. (Extra escape characters are for C++, of course.) Yet regex_match returns true for "3.6.5". I guessed that the problem might be in the '(...)?' expression just before the alternative operator '|', so I tried this: "[+-]?(\\d+|\\d+\\.\\d*|\\.\\d+)([Ee][+-]?\\d+)?". With this pattern regex_match returns false for "3.6.5". I am using it, but I consider it a workaround. Can someone explain what I have missed or whether this is a bug? -- Dick Hadsell 914-259-6320 Fax: 914-259-6499 Reply-to: hadsell@blueskystudios.com Blue Sky Studios http://www.blueskystudios.com 44 South Broadway, White Plains, NY 10601