HP C++ User Documentation

Standard C++ LibraryCopyright 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