Standard C++	Library
 		 Copyright 1996, Rogue Wave Software, Inc.

 NAME

   char_traits_ - A traits class	providing types	and operations to the
   basic_string container and iostream classes.

 SYNOPSIS

   #include <string>
   template <class charT> struct	char_traits
   struct char_traits<char>; .
   struct char_traits<wchar_t>;

 DESCRIPTION

   The char_traits struct provides elementary operations	to
   instantiations of basic_string and iostream classes.  As with all
   traits classes, char_traits is used to specialize	the behavior
   of	a template.  In	this case, the traits class	provides
   functions based on character type to the basic_string template
   and to the templates that are part of the iostreams library.

   Specializations of char_traits are provided for char and wchar_t.
   These are used to define, respectively, string and wstring,	 cout
   and wcout, etc.

 INTERFACE

   template <class charT> struct	char_traits .
   {
   typedef charT			   char_type;
   typedef int			   int_type;
   typedef streampos		   pos_type;
   typedef streamoff		   off_type;
   typedef mbstate_t		   state_type;

   static void assign (char_type&, const	char_type&);
   static char_type* assign (char_type*,	size_t,	const char_type&);

   static bool eq (const	char_type&, const char_type&);
   static bool lt (const	char_type&, const char_type&);

   static int compare (const char_type*,	const char_type*, size_t);
   static size_t	length (const char_type	* s);
   static const char_type*
    find	(const char_type*, int,	const char_type&);
   static char_type* move (char_type*,  const char_type*, size_t);
   static char_type* copy (char_type*,  const char_type*, size_t);

   static int_type not_eof(const	int_type& c);
   static char_type to_char_type(const int_type&	c);
   static int_type to_int_type(const char_type& c);
   static bool eq_int_type(const	int_type& c1, const int_type& c2);
   static int_type eof();
   };

 TYPE

   char_type
      The basic character type. Same as the template parameter.

   int_type
      A type that  can represent all the character values
      of char_type as	well as	and end	of file	value.

   pos_type
      A type used to represent a	position within	a stream buffer.

   off_type
      A type used to represent an offset	to a  position within a	stream
      buffer.

   state_type
      A type used to represent the state	class or type that is applied
      to the codecvt facet.  This type is only relevant	for streams
      with a underlying character type that is multi-byte.

 OPERATIONS

   static
   void assign(char_type& c1, const char_type& c2)
      Assigns one character value to another.  The value	of c2 is
      assigned to c1.

   static
   char_type* assign(char_type* s, size_t n, const char_type& a)
      Assigns one character value to n elements of a character array.
      The value of a	is assigned to n elements of s.

   static
   bool eq(const	char_type& c1, const char_type&	c2)
      Returns true if c1	equals c2.

   static
   bool lt(const	char_type& c1, const char_type&	c2)
      Returns true if c1	is less	than c2.

   static
   int compare(const char_type* s1, const char_type* s2,
 	     size_t n)
      Compares n values from s1 with n values	from s2.  Return 1 if
      s1 is greater than s2, -1 if s1	is less	than s2, or 0 if they
      are equal.

   static
   size_t length(const char_type	* s)
      Returns the length	of the null terminated character array s.  The
      eos terminator	is not counted.

   static
   const	char_type* find(const char_type* s, int	n,
 	const char_type& a)
      Looks for the value of a in s.  Only	n elements of s	are
      examined. Returns a pointer to	the matched element if one is
      found.  Otherwise	returns	s + n.

   static
   char_type* move(char_type* s1, const char_type* s2, size_t n)
      Moves n values from s1 to s2.  The	ranges of (s1,s1+n) and
      (s2,s2+n) may overlap.

   static
   char_type* copy(char_type* s1, const char_type* s2, size_t n)
      Copy n values from	s1 to s2. The ranges of	(s1,s1+n) and
      (s2,s2+n)	may not overlap.

   static
   int_type not_eof(const int_type& c)
      Returns c if c is not equal to eof(),  otherwise returns 0.

   static
   int_type to_char_type(const int_type&	c)
      Returns the char_type representation of c.	 This value may	not be
      useful if	no such	representation exists.

   static
   int_type to_int_type(const char_type&	c)
      Returns the int_type representation of c.

   static
   bool eq_int_type(const int_type& c1, const int_type& c2)
      Returns true if c1	equals c2.

   static
   int_type eof()
      Returns EOF.

 SEE ALSO

   basic_string,	traits,	basic_ostream, basic_istream, cout, cin,
   wcout,	wcin

 STANDARDS CONFORMANCE
   ANSI X3J16/ISO WG21 Joint C++	Committee