Chapter 1

Dynamic buffers are also used to store global and rich text, derived from CEditableText,
part of the Text and Text Attributes API defined in txt*.h headers. Segmented buffers are
particularly efficient at handling the kind of operations required by intensive word processing.
The editable text APIs include InsertL(), Read(), and Delete() with specifications
similar to those of CBufBase. However, the position argument in all these functions is a
character position, not a byte position: Unicode uses two bytes per character. The SDK
includes full documentation on rich text, and a pretty example project in
\Examples\AppFramework\Text.
8.1.3 Collections
A collection class is one that holds a number of objects. In Symbian OS, collections are
provided by a wide range of arrays and lists. The definitions for arrays and lists and for their
supporting classes can be found either in e32std.h or in e32base.h, (descriptor arrays
are defined in badesca.h). All are documented in the SDK, many with example code
fragments showing how they are used. This section summarizes the types of collection
classes available, describes the key properties of the concrete collection classes, and
provides a quick selection guide.
What types of collection are available?
RArray classes:
� use flat storage only,
� support sorting and searching using a comparator function and can ensure
uniqueness,
� provide specializations for common types, for instance, integers.
CArray classes:
� provide a choice of either flat or segmented storage,
� support sorting and searching using a key specification and can ensure uniqueness,
� provide several variants, for instance, fixed or variable size elements, packed data
� are generally slower and can be less easy to use than the RArray classes.
Descriptor arrays:
� provide a choice of either flat or segmented storage
� can contain 8-bit or 16-bit descriptors
� support sorting and searching and can ensure uniqueness
� provide variants that can store any type of descriptor or can hold pointers to the data.
Linked lists:
� support iterators for scanning through the list
� are available as singly and doubly linked lists; the link object must be a member of the
linked class.
TFixedArray:
� used when the number of elements is fixed and known at compile time
� should be used instead of traditional C++ arrays because they provide bounds
checking.
TArray:
� used for representing any array data in a generic way.
What are the main concrete containers?