| Re: How to see if variable is defined? [message #3357] |
Sat, 21 January 1995 10:22 |
ps
Messages: 14
Registered: September 1994
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Junior Member |
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Ralph Finch (rfinch@water.ca.gov) wrote:
: Is there a nice way of checking if a variable is defined?
: I have a widget_control command which removes a menu, and I need to
: see if the menu is defined before destroying it.
: --
: Ralph Finch 916-653-8268:voice 916-653-6077:fax
: rfinch@dop.water.ca.gov / finger for PGP public key
: "Nada burra la chamaca." A.G.
: Any opinions expressed are my own; they do not represent my employer
examine size(var). if s(s(0)+1) equal zero, var is undefined.
Or try the function keyword_set. But it has some problems if the
variable to be examined is zero.
Peter
------------------ Peter 'PIT' Suetterlin -----------------
| Kiepenheuer Institut | Sternfreunde Breisgau e.V |
| fuer Sonnenphysik | |
| 0761/3198-210 | 0761/71571 |
-<ps@kis.uni-freiburg.de>-<suettpet@sun1.ruf.uni-freiburg.de>--
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| Re: How to see if variable is defined? [message #3358 is a reply to message #3357] |
Sat, 21 January 1995 09:04  |
rivers
Messages: 228
Registered: March 1991
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Senior Member |
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In article <RFINCH.95Jan20094331@venice.water.ca.gov>, rfinch@water.ca.gov (Ralph Finch) writes:
> Is there a nice way of checking if a variable is defined?
>
> I have a widget_control command which removes a menu, and I need to
> see if the menu is defined before destroying it.
n_elements will tell you if a variable is defined:
IDL> print, n_elements(myvar)
will be 0 if myvar is not defined, 1 if myvar is a scalar, else number of
elements in array.
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