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

 NAME

   Input_Iterators  - A read-only, forward moving iterator.

 DESCRIPTION

   For a	complete discussion of iterators, see the Iterators section of
   this reference.

   Iterators are	a generalization of pointers that allow	a C++ program
   to uniformly interact with different data structures.  Input
   iterators are read-only,	forward	moving iterators that satisfy
   the requirements listed below.

 KEY TO ITERATOR	REQUIREMENTS

   The following	key pertains to	the iterator requirement descriptions
   listed below:

   a and	b   values of type X

   n   value of distance	type

   u, Distance, tmp and m   identifiers

   r   value of type X&

   t   value of type T

 REQUIREMENTS FOR INPUT ITERATORS

   The following	expressions must be valid for input iterators:

   X u(a)   copy	constructor, u == a

   X u =	a   assignment,	u == a

   a == b, a != b   return value	convertible to bool

   *a   a == b implies *a == *b

   ++r	returns	X&

   r++	return value convertible to const X&

   *r++	 returns type T

   a -> m   returns (*a).m

   For input iterators, a == b does not imply that ++a == ++b.

   Algorithms using input iterators should be single pass algorithms.
   That is they should not pass through the same	iterator twice.

   The value of type T does not have to be an lvalue.

 SEE ALSO

   iterators, output iterators

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