** no "and" in condition -seems to be assumed **;
%macro check;
%if %sysfunc(fileexist("&PV1."))
not %sysfunc(fileexist("&PV2."))
%then %do ;
%put "hello";
%end;
%put outside;
%mend;
%let pv1=<path/filename1>;
%let pv2=<path/filename2>;
%check;
Because 0 not 0 is equal to 1.
DN: Can you explain that for me/us?
Yes, I know that is the result that SAS gives, but I don't know why. I ran the following and got the following result:
%put NOTE1: %eval(0 not 0);
%put NOTE2: %eval(0 not 1);
%put NOTE3: %eval(1 not 1);
%put NOTE4: %eval(1 not 0);
results in:
NOTE1: 1
NOTE2: 0
NOTE3: 0
NOTE4: 1
I can see the answers, but have no idea what is being compared.
I don't know that I can explain it, at least not logically. :smileyshocked: I refer you to SAS Operators in Expressions
I vote for an error in the %eval function. I did read that section in the documentation and realize that not is supposed to be an operator, but the following won't work in a data step:
data test;
x1=0 not 0;
x2=0 not 1;
x3=1 not 1;
x4=1 not 0;
run;
Conversely, the following will run in a SAS macro:
%macro check;
%if %sysfunc(fileexist("&PV1."))
not %sysfunc(fileexist("&PV2."))
%then %do ;
%put "hello";
%end;
%put outside;
%put NOTE1: %eval(0 not 0);
%put NOTE2: %eval(0 not 1);
%put NOTE3: %eval(-0 not 1);
%put NOTE4: %eval(-0 not 0);
%mend;
%let pv1=<path/filename1>;
%let pv2=<path/filename2>;
%check
and will produce:
"hello"
outside
NOTE1: 1
NOTE2: 0
NOTE3: 0
NOTE4: 1
methinks that %eval() is only looking at the not 0 and not 1 parts and ignoring whatever comes before the 'not'. As a test of that hypothesis, the following works and provides the same result as the previous macro?
%macro check;
%if %sysfunc(fileexist("&PV1."))
not %sysfunc(fileexist("&PV2."))
%then %do ;
%put "hello";
%end;
%put outside;
%put NOTE1: %eval("cc" not 0);
%put NOTE2: %eval("xx" not 1);
%put NOTE3: %eval("yy" not 1);
%put NOTE4: %eval("zz" not 0);
%mend;
%let pv1=<path/filename1>;
%let pv2=<path/filename2>;
%check
As an aide to clarity
NOT
Is not the same operator as
NE
and the effect is quite different
Peter,
In case I didn't make myself clear in my last post, I think the reason it works is that %eval has an unaddressed fault that is allowing erroneous code to run without returning an error. As is, given a use like %eval("cc" not 0); the only thing being returned is the answer to "not 0" which would be 1. The first value (in this case "cc") isn't even being considered.
Art
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