Date:         Tue, 26 Nov 2002 16:45:16 -0500
Reply-To:     "Chakravarthy, Venky" <Venky.Chakravarthy@PFIZER.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         "Chakravarthy, Venky" <Venky.Chakravarthy@PFIZER.COM>
Subject:      Re: Question :Options and rules of using underscore
Comments: To: Knada <knada@acesag.auburn.edu>
Content-Type: text/plain; charset="iso-8859-1"

Nada,

I will write my reason.

I use beginning underscores to minimize the chance of conflict with existing
names from the input data set. In most cases, I do not need them in the
output data and the underscores easily catch my eye to make provision to get
rid of them. I tend to drop them easily with:

data outputdata ( drop = __: ) ;
   ..
run ;

Kind Regards,
__________________________
Venky Chakravarthy
E-mail: swovcc@hotmail.com

-----Original Message-----
From: Knada [mailto:knada@acesag.auburn.edu]
Sent: Tuesday, November 26, 2002 11:37 AM
To: SAS-L@listserv.uga.edu
Cc: Venky.Chakravarthy@pfizer.com; nada Nadarajah
Subject: Question :Options and rules of using underscore


SAS-L members,

I have been noticing recently many SAS programmers use leading or/
leading and trailing underscores in variable names as you see in the
following SAS code from Venky. In the past only we often use underscore
in ex: _n_ , to track observation number or in data step,  _null_ etc.

I couldn't find the rules/ options or guidelines of using underscores in
SAS documentation and would someone please explain this options or
direct me to read the guidelines /situations to use in programming code.

This is example code is from Venky:
-----------------------------------------------
%let numblanks = 3 ;
data withblanks ( drop = __i ) ;
    set needsblank ;
    by var2 notsorted ;
    array allnum _numeric_ ;
    array allcha _character_ ;
    output ;
    if last.var2 then
    do __i = 1 to &numblanks. ;
       do over allnum ;
         allnum = . ;
       end ;
       do over allcha ;
          allcha = " " ;
       end ;
       output ;
    end ;
run ;

----------------------------------------------

Thanks in advance.

Nada
--
  *****************************************
  *  Nada K. Nadarajah, PhD               *
  *  Research Fellow                      *
  *  Dept. Of Animal Sciences             *
  *  214 Upchurch Hall                    *
  *  Auburn University, AL 36849-5415     *
  *  USA                                  *
  *  Tel:334-844-1502 Fax: 334-844-1519   *
  *  e-mail knada@acesag.auburn.edu       *
  *                                       *
  *****************************************


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