The HDF_DF24_LASTREF function returns the reference number of the most recently read or written 24-bit image in an HDF file.

Examples

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; Open an HDF file.

h=HDF_OPEN('myhdf.hdf') 

PRINT, HDF_DF24_LASTREF() 

; IDL prints 0, meaning that the call was successful, 

; but no reference number was available.

; Create a 3D array, representing a 24-bit image:

a = BINDGEN(3,100,100)   

; Write the 24-bit image to the file:

HDF_DF24_ADDIMAGE, 'myhdf.hdf', a

PRINT, HDF_DF24_LASTREF()

; IDL prints a reference number for the last operation 

; (for example, 2). Note the reference number is not 

; simply a 1-based "image number"; the reference number 

; could easily be "2" or "3", etc.

; Write another image to the file:

HDF_DF24_ADDIMAGE, 'myhdf.hdf', a   

; Print the last reference number:

PRINT, HDF_DF24_LASTREF()

PRINT, HDF_DF24_NIMAGES('myhdf.hdf')

; IDL prints "2" because we’ve written two images to the file.

; Close the file

HDF_CLOSE, h

Syntax

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Result = HDF_DF24_LASTREF( )

Return Value

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Returns the reference number of the most recently read or written image.

Arguments

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None

Keywords

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None

Version History

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4.0	Introduced

See Also

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HDF_DF24_ADDIMAGE, HDF_DF24_GETIMAGE, HDF_DF24_GETINFO, HDF_DF24_NIMAGES, HDF_DF24_READREF, HDF_DF24_RESTART, HDF_DFR8_LASTREF