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©Copyright 1999 Rogue Wave Software

Random Access Iterators


     Iterator

Summary

An iterator that reads and writes, and provides random access to a container.

Contents

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. Random access iterators can read and write, and provide random access to the containers they serve. These iterators satisfy the requirements listed below.

Key to Iterator Requirements

The following key pertains to the iterator requirements 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 Random Access Iterators

The following expressions must be valid for random access iterators:

X u u might have a singular value
X() X() might be singular
X(a) copy constructor, a == X(a).
X u(a) copy constructor, u == a
X u = a assignment, u == a
a == b, a != b return value convertable to bool
*a return value convertable to T&
a->m equivalent to (*a).m
++r returns X&
r++ return value convertable to const X&
*r++ returns T&
--r returns X&
r-- return value convertable to const X&
*r-- returns T&
r += n Semantics of --r or ++r n times depending on the sign of n
a + n, n + a returns type X
r -= n returns X&, behaves as r += -n
a - n returns type X
b - a returns Distance
a[n] *(a+n), return value convertable to T
a < b total ordering relation
a > b total ordering relation opposite to <
a <= b !(a < b)
a >= b !(a > b)

Like forward iterators, random access iterators have the condition that a == b implies *a == *b.

There are no restrictions on the number of passes an algorithm may make through the structure.

All relational operators return a value convertable to bool.

See Also

Iterators, Forward Iterators, Bidirectional Iterators


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