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Validating Input

The pointer returned by astRead ([*]) could identify any class of Object--this is determined entirely by the external data being read. If it is necessary to test for a particular class (say a Frame), this may be done as follows using the appropriate member of the astIsA$<$Class$>$ family of functions:

int ok;

...

ok = astIsAFrame( object );

Note, however, that this will accept any Frame, so would be equally happy with a basic Frame or a SkyFrame. An alternative validation strategy would be to obtain the value of the Object's Class attribute and then test this character string, as follows:

#include <string.h>

...

ok = !strcmp( astGetC( object, "Class" ), "Frame" );

This would only accept a basic Frame and would reject a SkyFrame.


next up previous 264
Next: Storing an ID String with an Object
Up: Saving and Restoring Objects (Channels)
Previous: Saving and Restoring Multiple Objects

AST A Library for Handling World Coordinate Systems in Astronomy
Starlink User Note 211
R.F. Warren-Smith & D.S. Berry
25th February 2013
E-mail:starlink@jiscmail.ac.uk

Copyright (C) 2014 Science \& Technology Facilities Council