Scientific Data Formats: Hierarchical Data Format

HDF_DFAN_GETDESC

The HDF_DFAN_GETDESC procedure reads the description for the given tag and reference number in an HDF file.

Syntax

HDF_DFAN_GETDESC, Filename, Tag, Ref, Description [, /STRING]

Arguments

Filename

A scalar string containing the name of the file to be read.

Tag

The tag number.

Reference

The reference number.

Description

A named variable in which the description is returned as a vector of bytes.

If a description does not exist, the Description variable will contain either a 0L (long-integer zero) or a blank string, and a warning message will be printed. Warning messages can be suppressed by setting the !QUIET system variable to a non-zero value.

Keywords

STRING

Set this keyword to return the description as a string rather than a vector of bytes.

Examples

desc1 = 'FILE DESCRIPTION NUMBER 1'  
tag_image = 302  
file = 'DEMOdesc.hdf'  
fid = HDF_OPEN(file, /CREATE)  
HDF_DFR8_ADDIMAGE, file, DIST(10)  
HDF_DFAN_PUTDESC, file, tag_image, HDF_DFR8_LASTREF(), desc1  
; Read the description and return a vector of bytes:  
HDF_DFAN_GETDESC, file, tag_image, HDF_DFR8_LASTREF(), out_desc1  
HELP, out_desc1  
PRINT, STRING(out_desc1)  
; Read the description and return an IDL string variable:  
HDF_DFAN_GETDESC, file, tag_image, HDF_DFR8_LASTREF(), $  
    out_desc2, /STRING  
HELP, out_desc2  
HDF_CLOSE, fid  

OUT_DESC1       BYTE      = Array(25)  
  
FILE DESCRIPTION NUMBER 1  
  
OUT_DESC2       STRING    = 'FILE DESCRIPTION NUMBER 1'