| Test if variable is a string [message #33913] |
Tue, 04 February 2003 01:56  |
Carsten Dominik
Messages: 45
Registered: February 1998
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Member |
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Hello,
I must be blind: How do I test for the type of the object contained
in a variable? I am writing a procedure and want to allow one of the
arguments to be either a string or a number - but the program must of
course find out which it is?
This is my main problem with IDL: I am *never* able to correctly guess
the name of a function for a particular purpose.
So what is the magic word for determining the type of a variable?
Thanks.
- Carsten
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| Re: Test if variable is a string [message #34108 is a reply to message #33913] |
Mon, 17 February 2003 02:36  |
R.Bauer
Messages: 1424
Registered: November 1998
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Senior Member |
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M. Katz wrote:
Did you recognize the tname keyword of size?
IDL> print,size(10L,/tname)
LONG
regards
Reimar
> Here's a handy little function I've been using for years.
> var_type.pro
> I think I added a number of new type names back in 2001.
> If RSI adds more types in the future, they'll probably
> be appended to the list rather than change the existing list.
> In that case, you'll have to modify the list.
>
> So the function returns the type as a number. But if
> you set the /string keyword, you'll get a string containing
> the name of the type.
>
> For example:
> IDL> print, var_type(10L)
> 3
> IDL> print, var_type(10L, /s)
> Longword Integer
>
> ;+
> ; IDL function: var_type.pro
> ; for a given input variable, this function returns
> ; the type of that variable. The returned value is a number 0-15
> ; similar to the second-to-last field in the "size" function,
> ; or if the keyword "string" is used, a string.
> ;-
>
> function var_type, a, string=string
>
> s = ['Undefined','Byte','Integer','Longword
> Integer','Floating-point', $
> 'Double-precision floating','Complex
> floating','String','Structure', $
> 'Double-precision complex','Pointer','Object reference', $
> 'Unsigned Integer','Unsigned Longword Integer','64-bit
> Integer',$
> 'Unsigned 64-bit Integer']
>
> return, Keyword_set(string) ? s(size(a, /type)):size(a, /type)
> end
>
> I also have a closely related function called defined.pro that tests
> true-or-false, if a given variable is defined or not. It also uses
> size(x, /type), that's why I'm including it here.
>
> ;+
> ; IDL function: defined.pro
> ; For a given input variable, this function returns
> ; 1b if the variable is defined
> ; 0b if the variable is undefined
> ;-
>
> function defined, a
> return, (size(a, /type) NE 0)
> end
>
>
> Hope this helps,
>
> M. Katz
--
Reimar Bauer
Institut fuer Stratosphaerische Chemie (ICG-I)
Forschungszentrum Juelich
email: R.Bauer@fz-juelich.de
------------------------------------------------------------ -------
a IDL library at ForschungsZentrum Juelich
http://www.fz-juelich.de/icg/icg-i/idl_icglib/idl_lib_intro. html
============================================================ =======
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| Re: Test if variable is a string [message #34114 is a reply to message #34025] |
Sun, 16 February 2003 12:58 |
MKatz843
Messages: 98
Registered: March 2002
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Member |
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Here's a handy little function I've been using for years.
var_type.pro
I think I added a number of new type names back in 2001.
If RSI adds more types in the future, they'll probably
be appended to the list rather than change the existing list.
In that case, you'll have to modify the list.
So the function returns the type as a number. But if
you set the /string keyword, you'll get a string containing
the name of the type.
For example:
IDL> print, var_type(10L)
3
IDL> print, var_type(10L, /s)
Longword Integer
;+
; IDL function: var_type.pro
; for a given input variable, this function returns
; the type of that variable. The returned value is a number 0-15
; similar to the second-to-last field in the "size" function,
; or if the keyword "string" is used, a string.
;-
function var_type, a, string=string
s = ['Undefined','Byte','Integer','Longword
Integer','Floating-point', $
'Double-precision floating','Complex
floating','String','Structure', $
'Double-precision complex','Pointer','Object reference', $
'Unsigned Integer','Unsigned Longword Integer','64-bit
Integer',$
'Unsigned 64-bit Integer']
return, Keyword_set(string) ? s(size(a, /type)):size(a, /type)
end
I also have a closely related function called defined.pro that tests
true-or-false, if a given variable is defined or not. It also uses
size(x, /type), that's why I'm including it here.
;+
; IDL function: defined.pro
; For a given input variable, this function returns
; 1b if the variable is defined
; 0b if the variable is undefined
;-
function defined, a
return, (size(a, /type) NE 0)
end
Hope this helps,
M. Katz
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