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FindPreviousKey Method

Summary

Returns the previous item in the Dicom Dir Data Set with a specific key element type.

Syntax
C#
VB
Java
C++
public DicomElement FindPreviousKey( 
   DicomElement element, 
   bool tree 
) 
Public Function FindPreviousKey( _ 
   ByVal element As DicomElement, _ 
   ByVal tree As Boolean _ 
) As DicomElement 
public DicomElement findPreviousKey(DicomElement element, boolean tree) 
public: 
DicomElement^ FindPreviousKey(  
   DicomElement^ element, 
   bool tree 
)  

Parameters

element
An item in the Data Set.

tree
true to evaluate the Data Set as a tree; false to evaluate the Data Set as a list.

Return Value

The previous item in the Data Set with a specified key element type, or a null reference (Nothing in VB) if a previous item with the specified key element type was not found.

Remarks

Note: This method does not specify a key element type to use when searching. However the key element type that was used in the last call to FindFirstKey or FindLastKey is used by default when searching. For the sake of the following illustrations, the order of siblings is top to bottom.

If the Data Set is evaluated as a tree structure, this method returns the previous item on the same level as element, with the same parent as element, that has key element type key.

Please note that the numbering of the items of interest in this first illustration is arbitrary and does not imply order.

fndfttr.gif
If the passed object points to: The method returns an object pointing to:
Item 1 The previous sibling (same level, same parent) of Item 1 that has key element type key, if such an item exists. If such an item does not exist, the method returns null.
Item 2 The previous sibling (same level, same parent) of Item 2 that has key element type key, if such an item exists. If such an item does not exist, the method returns null.
Item 3 The previous sibling (same level, same parent) of Item 3 that has key element type key, if such an item exists. If such an item does not exist, the method returns null.

If the Data Set is evaluated as a list, this method returns the previous item in the entire list that has key element type key.

Please note that the numbering of the items in the following illustration does indicate the order of the items when the Data Set is evaluated as a list.

fndftlst.gif
If the passed object points to: The method returns an object pointing to:
Item 1 The previous item in the list that has key element type key, if such an item exists. If an item with key element type key is not found, null is returned.
Item 14 The previous item in the list that has key element type key, if such an item exists. If an item with key element type key is not found, null is returned.
Item 22 The previous item in the list that has key element type key, if such an item exists. If an item with key element type key is not found, null is returned.

The following methods will also help you find elements in the Data Set with a specific key element type:

FindFirstKey

FindLastKey

FindNextKey

Example

For an example, refer to Reset.

Requirements

Target Platforms

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