+ lexical_error(const std::string &w): runtime_error(w) { }
+ virtual ~lexical_error() throw() { }
+};
+
+
+class format_mismatch: public lexical_error
+{
+public:
+ format_mismatch(const std::string &w): lexical_error(w) { }
+ virtual ~format_mismatch() throw() { }