Symbian Programming

1
Symbian Programming

• Part V
• Programming Symbian devices with Symbian C

Arrays
2
Content

• Array classes
• Linked lists

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Fixed Arrays

• TFixedArraylttype,sizegt name
• TFixedArrayltTInt,10gt myNumbers
• for(TInt j 0 j lt 10 j)
• myNumbersj j

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Descriptor Arrays

• CDesC16ArrayFlat
• CDesC16ArraySeg
• CDesC8ArrayFlat
• CDesC8ArraySeg
• CDesCArrayFlat
• CDesCArraySeg

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Descriptor Arrays

• CPtrC16Array
• CPtrC8Array
• CPtrCArray
• Last three only available flat

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CDesC

• Array of HBufC pointers
• Array class allocates a HBufC automatically when
  a CDesC is added
• Content is copied into the HBufC

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Example

• _LIT(KStr1, "Coding")
• _LIT(KStr2, " Symbian")
• TBufClt10gt Test1(KStr1)
• TBufClt10gt Test2(KStr2)
• CDesCArrayFlat myArray
• new (ELeave) CDesCArrayFlat(5)
• CleanupStackPushL(myArray)

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Example (cont.)

• myArray-gtAppendL(Test1)
• myArray-gtAppendL(Test2)
• CleanupStackPopAndDestroy()

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Dynamic Arrays

• Based on dynamic Buffers
• Templated
• Any type elements
• For Example
• CArrayFixFlatltclass Tgt
• CArrayFixSegltclass Tgt
• CArrayPtrFlatltclass Tgt
• CArrayPtrSegltclass Tgt
• RArrayltclass Tgt
• RPointerArrayltclass T

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RArray and RPointerArray

• RArray
• simple array of objects
• objects must have fixed length
• max 640 bytes elemet size
• RPointerArray
• array of pointers to objects
• arbitrarily large elements

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RArray

• RArrayltanyObjgt array
• Size not preallocated
• Can be declared as an automatic
• goes into stack
• The dynamic buffer is in the heap
• Like with resources call Close when deleting

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Granularity

• Can be changed
• default 8
• RArrayltanyObjgt array(10)

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Key order and Key offset

• Elements can be assigned a key
• TInt
• Key order can be used to sort the array
• Class offset can be declared when creating the
  array RArrayltanyObjgt array(10, 12)
• Default 0, multiple of 4
• _FOFF(class,member)

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Inserting

• Insert()
• InsertSignedKeyOrder()
• InsertUnsignedKeyOrder()
• InsertInOrder()
• InsertInOrderAllowRepeat()

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Callback

• You can create your own callback function for
  comparing two values
• wrapper class TLinearOrder
• InsertInOrder(const T aEntry,
• TLinearOrder ltTgt AOrder)
• the callback function in TLinearOrder

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Appending and searching

• Append()
• Array automatically allocates memory as needed
• Find()
• FindInOrder()
• FindInSignedOrder()
• FindInUnsignedOrder()
• The 3 last ones assume the array is in order

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Searching

• Returns either an index or KErrNotFound
• Find(const T anObject)
• compares keys in the array and anObject
• also possible to create a callback using
  TIdentityRelation

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Sorting

• Sort()
• SortSigned()
• SortUnsigned()
• Sort(TLinearOrder) callback can be used
• Others...
• Remove(TInt index)
• Reset() Close() releases heap memory

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RPointerArray

• Like RArray, excepts holds only pointers
• granularity
• no keys, but you can use TLinearOrder
• Append
• Insert
• etc...

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Linked Lists

• TDblQueltclass Tgt
• doubly linked list
• AddFirst()
• AddLastC()
• First()
• Last()

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Linked Lists

• LinkTDblQueLink
• TDblQueLink.Enque() // insert
• TDblQueLink.Deque() // delete
• IteratorTDblQueIterltmyObjgt iter (LinkList)

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Collection classes

• Arrays
• CArray
• Flexible
• RArray
• Efficient

23
Console applications

• Testing and experimenting with strings etc. can
  be easier with a simple console app than with a
  full blown GUI
• In Carbide
• File-gtNew-gtSymbian OS C project
• select console application
• Creates a project with a single source code file
• Code your functionality in MainL and other
  functions