>  Docs Center  >  Libraries  >  ASTROLIB  >  TAG_EXIST






      To test whether a tag name exists in a structure.


      Routine obtains a list of tagnames and tests whether the requested one
      exists or not. The search is recursive so if any tag names in the
      structure are themselves structures the search drops down to that level.
      (However, see the keyword TOP_LEVEL).

Calling Sequence

      status = TAG_EXIST(str, tag, [ INDEX =, /TOP_LEVEL, /QUIET ] )

Input Parameters

      str - structure variable to search
      tag - tag name to search for, scalar string


      Function returns 1b if tag name exists or 0b if it does not.

Optional Input Keyword

      /TOP_LEVEL = If set, then only the top level of the structure is
      /QUIET - if set, then do not print messages if invalid parameters given
      /RECURSE - does nothing but kept for compatibility with the
                  Solarsoft version for which recursion is not the default

Optional Output Keyword

      INDEX = index of matching tag, scalar longward, -1 if tag name does
              not exist


      Determine if the tag 'THICK' is in the !P system variable
      IDL> print,tag_exist(!P,'THICK')

Procedure Calls


Modification History

      Written, C D Pike, RAL, 18-May-94
      Passed out index of matching tag, D Zarro, ARC/GSFC, 27-Jan-95
      William Thompson, GSFC, 6 March 1996 Added keyword TOP_LEVEL
      Zarro, GSFC, 1 August 1996 Added call to help
      Use SIZE(/TNAME) rather than DATATYPE() W. Landsman October 2001
      Added /RECURSE and /QUIET for compatibility with Solarsoft version
                W. Landsman March 2009
      Slightly faster algorithm W. Landsman July 2009
      July 2009 update was not setting Index keyword W. L Sep 2009.
      Use V6.0 notation W.L. Jan 2012
        Not setting index again, sigh W.L./ K. Allers Jan 2012

© 2022 L3Harris Geospatial Solutions, Inc. |  Legal
My Account    |    Contact Us