LDicomDS::FindFirstElement

#include "Ltdic.h"

pDICOMELEMENT LDicomDS::FindFirstElement(pElement, nTag, bTree)

pDICOMELEMENT pElement;	/* pointer to a DICOMELEMENT structure */
L_UINT32 nTag;	/* tag that indicates the element to find */
L_BOOL bTree;	/* flag that indicates how to evaluate the Data Set */

Returns a pointer to the first item in the Data Set with the specified tag.

Parameter	Description
pElement	Pointer to a DICOMELEMENT structure within the Data Set.
nTag	Tag that specifies the item to find. For a list of default tag values, refer to Data Element Tag Constants.
bTree	Flag that indicates how the Data Set will be evaluated. Possible values are:
	Value	Meaning
	TRUE	Evaluate the Data Set as a tree.
	FALSE	Evaluate the Data Set as a list.

Returns

!NULL	A pointer to a DICOMELEMENT structure that contains the first item in the Data Set with the specified tag.
NULL	An item with the specified tag was not found.

Comments

If the Data Set is evaluated as a tree structure, this function returns the first item on the same level as pElement with the same parent as pElement, that has tag nTag.

For the sake of these illustrations, the order of siblings is top to bottom. Therefore first is evaluated top to bottom.

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

$image\FndFtTr.gif$

If the passed pointer points to :	The function returns a pointer to :
Item 1	The first sibling (same level, same parent) of Item 1 that has tag nTag, if such an item exists. If such an item does not exist, the function returns NULL.
Item 2	The first sibling (same level, same parent) of Item 2 that has tag nTag, if such an item exists. If such an item does not exist, the function returns NULL.
Item 3	The first sibling (same level, same parent) of Item 3 that has tag nTag, if such an item exists. If such an item does not exist, the function returns NULL.

If the Data Set is evaluated as a list, this function returns the first item in the entire list that has tag nTag. The search begins at the top of the list.

For the sake of these illustrations, the order of siblings is top to bottom. Therefore first is evaluated top to bottom.

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

$image\FndFtLst.gif$

If the passed pointer points to :	The function returns a pointer to :
Item 1	The first item in the list that has tag nTag, if such an item exists. Searching begins at the top of the list. If an item with tag nTag is not found, NULL is returned.
Item 14	The first item in the list that has tag nTag, if such an item exists. Searching begins at the top of the list. If an item with tag nTag is not found, NULL is returned.
Item 22	The first item in the list that has tag nTag, if such an item exists. Searching begins at the top of the list. If an item with tag nTag is not found, NULL is returned.

The following functions will also help you find elements in the Data Set with a specific tag:

LDicomDS::FindLastElement

LDicomDS::FindPrevElement

LDicomDS::FindNextElement

The following functions will help you find specific modules in the Data Set:

LDicomDS::FindModule

LDicomDS::FindIndexModule

Required DLLs and Libraries

LTDIC

For a listing of the exact DLLs and Libraries needed, based on the toolkit version, refer to Files To Be Included With Your Application

See Also

Functions:	LDicomDS::FindLastElement, LDicomDS::FindPrevElement, LDicomDS::FindNextElement, LDicomDS::FindModule, LDicomDS::FindIndexModule
Topics:	Working with Data Sets
	How to Disable the Automatic Loading of the default DICOM IOD Table

Example

This example displays in a list-box control the names of all elements.

L_INT LDicomDS_FindFirstElementExample(CListBox *pDlg)
{
   LDicomDS*      pDS;
   pDICOMELEMENT  pElement;
   pDICOMTAG      pTag;
   L_TCHAR        szUnknown[]=TEXT("Unknown");
   L_TCHAR*       p;
   pDS = new LDicomDS(NULL);
   pDS->InitDS( CLASS_XA_BIPLANE_IMAGE_STORAGE_RETIRED, 0); 
   pElement = pDS->FindFirstElement(NULL, TAG_SOP_CLASS_UID, FALSE);
   if (pElement != NULL)
   {
      pTag = LDicomTag::Find(pElement->nTag);
      if (pTag != NULL)
      {
         p = pTag->pszName;
      }
      else
      {
         p = szUnknown;
      }
      pDlg->AddString(p);
      pElement = pDS->FindNextElement(pElement, FALSE);
   }
   delete pDS;
   return DICOM_SUCCESS;
}