charT Requirements

Type charT used a template argument to class template basic_regex, must have a trivial default constructor, copy constructor, assignment operator, and destructor. In addition the following requirements must be met for objects; c of type charT, c1 and c2 of type charT const, and i of type int:

Expression	Return type	Assertion / Note / Pre- / Post-condition
charT c	charT	Default constructor (must be trivial).
charT c(c1)	charT	Copy constructor (must be trivial).
c1 = c2	charT	Assignment operator (must be trivial).
c1 == c2	bool	true if c1 has the same value as c2.
c1 != c2	bool	true if c1 and c2 are not equal.
c1 < c2	bool	true if the value of c1 is less than c2.
c1 > c2	bool	true if the value of c1 is greater than c2.
c1 <= c2	bool	true if c1 is less than or equal to c2.
c1 >= c2	bool	true if c1 is greater than or equal to c2.
intmax_t i = c1	int	charT must be convertible to an integral type. Note: type charT is not required to support this operation, if the traits class used supports the full Boost-specific interface, rather than the minimal standardised-interface (see traits class requirements below).
charT c(i);	charT	charT must be constructable from an integral type.