Routines (alphabetical) > Routines: H > HDF Routines > HDF_NUMBER

# HDF_NUMBER

The HDF_NUMBER function returns the number of tags in an HDF file or the number of references associated with a given tag.

## Syntax

Result = HDF_NUMBER( FileHandle [, TAG=integer] )

## Return Value

Returns either the number of tags in the file or the number of references associated with the specified tag.

## Arguments

### FileHandle

The HDF file handle returned from a previous call to HDF_OPEN.

## Keywords

### TAG

Set this keyword to an integer tag number or the string `'*'`. If this keyword is set to a tag number, HDF_NUMBER returns the number of references associated with the given tag. If this keyword is set to the string `'*'`, or is not specified, HDF_NUMBER returns the total number of tags in the HDF file.

## Version History

Pre 4.0 | Introduced