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Date:         Tue, 5 Sep 2006 12:38:39 -0500
Reply-To:     Yu Zhang <zhangyu05@GMAIL.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Yu Zhang <zhangyu05@GMAIL.COM>
Subject:      Re: Check if macro parameter is empty
In-Reply-To:  <>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Dear Members,

After I tried out the following code, I think the cause of the problem should be parenthesis,( ). I am not sure what or how the %if statement is evaluated. Apprently, when SAS macro facility saw a pair of parenthesis, it will expect something. Could someone kindly provide more information about %if statement evaluation? If I am totally looking at wrong target, please let me know.

Thank you much!


/* I got same error meassge, even after I took off all the %,&'s */ %let macrolist=hello(); %macro MyMacro; %if &macrolist ne %then %do; %put macrolist is >&macrolist<; %end; %mend; %MyMacro;

On 9/5/06, Ian Whitlock <> wrote: > > Yom, > > Some more points: > > 1) You will learn faster if you explain the real problem as > opposed to saying your solution has an error, since you > will then find out about better solutions than the one > you thought of and guide the helper in how to answer the > error you are facing. > > 2) Testing > > %length(&macvar) > 0 > > is safer than > > &macvar ne > > because fewer thing need to be hidden by macro quoting. > > 3) It is a very bad habit to bury macro definitions inside macros. > Remember that the inner macro is compiled each and every time the > outer macro is executed and nothing is accomplished by nesting > macro definitions other than possibly preventing you from good > design habits. > > 4) It is often better leave the %-sign of a macro invocation > given in a parameter. In version 8.2+ > > %let mac = mymac(parm=abc) ; > %&mac > > works quite well and saves a lot of quoting. > > 5) The macro compile time quoting functions %STR and %NRSTR leave > things hidden at macro execution time. Hence they should be > used when hiding a symbol at execution time. > > 6) The execution time quoting functions, %BQUOTE, %NRBQUOTE, and %SUPERQ > should not be used to hide a symbol; they only be used when the > result of resolving > will reveal a problem symbol. It is worth forgetting about %BQUOTE > and > %NRBQUOTE to standardize on %SUPERQ. Anytime the prior functions are > required the macro is too tricky to work anyway. > > Ian Whitlock > ================ > Date: Tue, 5 Sep 2006 17:13:09 +0200 > Reply-To: yom <yomsas@GMAIL.COM> > Sender: "SAS(r) Discussion" > From: yom <yomsas@GMAIL.COM> > Subject: Re: Check if macro parameter is empty > Comments: To: toby dunn <> > In-Reply-To: <BAY123-F14A01BF608027DB0C086CBDE300@phx.gbl> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > Thank you very much ! Tonight I will go to bed being less stupid ! > Best regards, > yom > <snip> >

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