topic Re: Why Can I Use _CHARACTER_ as a Variable Name? in SAS Programming

Why Can I Use _CHARACTER_ as a Variable Name?

Howles — Thu, 16 Jun 2011 02:10:20 GMT

Consider:

[pre]
335 data _null_ ;
336 _all_ = 123 ;
ERROR: Cannot use _all_ as a variable name.
337 _numeric_ = 456 ;
ERROR: Cannot use _numeric_ as a variable name.
338 _character_ = 789 ;
339 run ;
[/pre]

There's no ERROR after line 338. _CHARACTER_ can be used as a variable name (not that this would be a good idea).

Can anyone provide a good reason for the asymmetry with _NUMERIC_ and _ALL_, which trigger errors when used as variable names?

SAS 9.2 2M3 on Win XP.

Thanks.

Re: Why Can I Use _CHARACTER_ as a Variable Name?

data_null__ — Thu, 16 Jun 2011 02:26:33 GMT

I cannot answer the question but though this was interesting.

[pre]
2326 data _null_;
2327 _char_ = 1233;
ERROR: Cannot use _char_ as a variable name.
2328 run;
[/pre]

Re: Why Can I Use _CHARACTER_ as a Variable Name?

MichelleHomes — Thu, 16 Jun 2011 03:14:31 GMT

This is a Special SAS Name List (a type of SAS Variable List) and as such is a reserved word...

Check out doco - http://support.sas.com/documentation/cdl/en/lrcon/62955/HTML/default/viewer.htm#a000695105.htm

Hope this helps,
Michelle

Re: Why Can I Use _CHARACTER_ as a Variable Name?

sbb — Thu, 16 Jun 2011 08:35:56 GMT

To the OP: if you want to pursue this type of anomaly, you will be best served by going directly to SAS Tech Support and opening a track to ask the question, given what you have uncovered.

Scott Barry
SBBWorks, Inc.

Re: Why Can I Use _CHARACTER_ as a Variable Name?

Peter_C — Thu, 16 Jun 2011 16:24:32 GMT

Michelle
I can understand why _character_ is reserved, but cannot find reference at the link you provided (nor elsewhere) to _char_

Is it just an undocumented alternative to _character_ ?

peterC

Re: Why Can I Use _CHARACTER_ as a Variable Name?

data_null__ — Thu, 16 Jun 2011 18:58:45 GMT

> Is it just an undocumented alternative to _character_
> ?

I thought _CHAR_was documented but cannot find documentation in relation to SAS Variable List used in data/proc steps.

It would appear to me that the "data step team" at SAS thinks _CHAR_ is "something".

Perhaps _CHARACTER_ is allowed to provide some backward compatibility from days of old.

Further fiddling with _CHARACTER_ produced interesting context sensitive results.

[pre]
2614 options stimer=0 fullstimer=0 missing=.;
2615 data test(keep=_character_);
2616 if 0 then set sashelp.class;
2617 *_char_ = 1233;
2618 _character_ = '9';
2619 cm = cmiss(of _character_);
2620 put _character_;
2621 put (_character_)(=);
2622 put _character_=;
2623 *_numeric_ = '0';
2624 array c

_character_;
2625 put (c

) (=);
2626 put _all_;
2627 output;
2628 stop;
2629 run;

9
Name= Sex= _character_=9
_character_=9
Name= Sex= _character_=9
Name= Sex= Age=. Height=. Weight=. _character_=9 cm=2 _ERROR_=0 _N_=1
NOTE: The data set WORK.TEST has 1 observations and 3 variables.

2630 data _null_;
2631 set test;
2632 put _all_;
2633 run;

Name= Sex= _character_=9 _ERROR_=0 _N_=1
[/pre]

Re: Why Can I Use _CHARACTER_ as a Variable Name?

Peter_C — Thu, 16 Jun 2011 21:15:38 GMT

Stunning

_char_ is not valid as a var name
It has the effect of _character_ when used in a keep list
I found no corresponding abbreviation of _numeric_

Re: Why Can I Use _CHARACTER_ as a Variable Name?

Howles — Sat, 18 Jun 2011 23:56:12 GMT

We don't seem to have a solid explanation, so I guess it's time to put this in front of Tech Support.

The point is that _CHARACTER_ is *not* reserved, at least not in the way _ALL_ is.

Also notice that enforcement is more or less limited to the DATA step. Here is a PROC step which is happy to permit use of variable names which are not allowed (or at least discouraged) in the DATA step.

[pre]
proc summary data=sashelp.class(obs=3) nway ;
class sex ;
output out=badnames(rename = (_freq_ = _n_ _type_=_error_) )
min(age) = _numeric_
max(age) = _character_
mode(age)= _all_
;
run ;
[/pre]

Of course referencing these names will be a problem.

Another slightly interesting bit of evidence. When this code

[pre]
proc print ;
var _numeric_ _character_ _char_ _all_ _notmetoo_ ;
run ;
[/pre]

is placed in the enhanced editor, the first four specs in the VAR statement are recognized and thus colored blue rather than black.