I'm working with CBuilder6 and boost boost_1_34_1 and found, that

regex expression1("[[:print:]]+");

matches with regex_search the whole string:

testtext = "ab\r\ncd ef";

including the linebreak and the white space. I had assumed, that the print-class would consist exactly in the set of characters for which the standard function isprint returns true but isprint returns false for the space characters. Is there there any documentation with the exact enumerations of the different character sets?

On Windows the default behavior is to use ::GetStringTypeEx to determine character classifications: this puts \r and \n as "space" characters which certainly are printable. If you wish you could use basic_regex as the regex type, and get the behavior you're expecting as internally it calls std::isctype, or you could use: basic_regex as the regex type, and character classification would then depend on std::locale. In both these cases though, exactly how \r and \n are classified would depend on the platform and the locale in effect at the time - unless you're explicitly using the "C" locale in which case you *should* get consistent behavior, modulo any C std lib bugs. HTH, John.