Microsoft Foundation Classes (mfc.hlp) (
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class CObArray
◄CObject► ◄Up► ◄Contents► ◄Index► ◄Back►
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Description
The CObArray class supports arrays of CObject pointers. These object
arrays are similar to C arrays, but they can dynamically shrink and grow
as necessary.
Array indexes always start at position 0. You can decide whether to fix
the upper bound or allow the array to expand when you add elements past
the current bound. Memory is allocated contiguously to the upper bound,
even if some elements are null.
The elements of a CObArray object must fit in one 64K segment together
with approximately 100 allocation overhead bytes. If CObject pointers
are 16-bit near pointers (as they are in the small and medium memory
models), then an array size limit is about 32,000 elements, but because
there is only one data segment, the objects themselves will probably
exhaust memory before the array does. If CObject pointers are 32-bit far
pointers (as they are in the compact and large memory models), then an
array size limit is about 16,000 elements.
As with a C array, the access time for a CObArray indexed element is
constant and is independent of the array size.
CObArray incorporates the IMPLEMENT_SERIAL macro to support
serialization and dumping of its elements. If an array of CObject
pointers is stored to an archive, either with the overloaded insertion
operator or with the Serialize member function, each CObject element is,
in turn, serialized along with its array index.
If you need a dump of individual CObject elements in an array, you must
set the depth of the CDumpContext object to 1 or greater.
When a CObArray object is deleted, or when its elements are removed,
only the CObject pointers are removed, not the objects they reference.
#include <afxcoll.h>
See Also
◄CStringArray►, ◄CPtrArray►, ◄CByteArray►, ◄CWordArray►, ◄CDWordArray►
Derivation
Array class derivation is similar to list derivation. For details on the
derivation of a special-purpose list class, see the tutorial in the
<Class Library User's Guide>.
NOTE: You must use the IMPLEMENT_SERIAL macro in the implementation of
your derived class if you intend to serialize the array.
Public Members
Construction/Destruction
◄CObArray► Constructs an empty array for CObject pointers.
◄~CObArray► Destroys a CObArray object.
Bounds
◄GetSize► Gets the number of elements in this array.
◄GetUpperBound► Returns the largest valid index.
◄SetSize► Sets the number of elements to be contained in this
array.
Operations
◄FreeExtra► Frees all unused memory above the current upper bound.
◄RemoveAll► Removes all the elements from this array.
Element Access
◄GetAt► Returns the value at a given index.
◄SetAt► Sets the value for a given index; array not allowed to
grow.
◄ElementAt► Returns a temporary reference to the element pointer
within the array.
Growing the Array
◄SetAtGrow► Sets the value for a given index; grows the array if
necessary.
◄Add► Adds an element to the end of the array; grows the array
if necessary.
Insertion/Removal
◄InsertAt► Inserts an element (or all the elements in another array)
at a specified index.
◄RemoveAt► Removes an element at a specific index.
Operators
◄operator []► Sets or gets the element at the specified index.
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