SAS Quoting Function %STR

[kisumsam]

Hello, I am learning macro quoting functions and I got some questions. Hope some of you expert can help 🙂

Below is the code I ran:

options mlogic mprint;
%macro translate (var);
%if &var = %str(EQ) %then %put The result is correct;
%else %put The result is incorrect;
%mend;
%translate(EQ)

The mlogic shows the condition is false :

MLOGIC(TRANSLATE): Beginning execution.

MLOGIC(TRANSLATE): Parameter VAR has value EQ

MLOGIC(TRANSLATE): %IF condition &var = EQ is FALSE

MLOGIC(TRANSLATE): %PUT The result is incorrect

The result is incorrect

MLOGIC(TRANSLATE): Ending execution.

I'm assuming this is because the &var needs to masked as well in the %IF condition. Because I want to mask the resolved value, I used the %bquote quoting function:

%macro translate (var);
%if %bquote(&var) = %str(EQ) %then %put The result is correct;
%else %put The result is incorrect;
%mend;
%translate(EQ)

It works which is great:

MLOGIC(TRANSLATE): Beginning execution.

MLOGIC(TRANSLATE): Parameter VAR has value EQ

MLOGIC(TRANSLATE): %IF condition %bquote(&var) = EQ is TRUE

MLOGIC(TRANSLATE): %PUT The result is correct

The result is correct

MLOGIC(TRANSLATE): Ending execution.

And now, I'm just doing a quick experiment and I used the %str instead of the %bquote function:

%macro translate (var);
%if %str(&var) = %str(EQ) %then %put The result is correct;
%else %put The result is incorrect;
%mend;
%translate(EQ)

It also works. 

MLOGIC(TRANSLATE): Beginning execution.

MLOGIC(TRANSLATE): Parameter VAR has value EQ

MLOGIC(TRANSLATE): %IF condition &var = EQ is TRUE

MLOGIC(TRANSLATE): %PUT The result is correct

The result is correct

MLOGIC(TRANSLATE): Ending execution.

So my question is, why does the %str works when I use it on the &var. From what I understand, the %str masks the value in compile time where the &var value is not resolved. So when it comes the execution time, the resolved value (which is EQ) should not be masked and this should cause %IF condition to fail.

Could anyone explain why the %str function works in this example?

[Ksharp]

options mlogic mprint;
%macro translate (var);
%if %bquote(&var) = %str(EQ) %then %put The result is correct;
%else %put The result is incorrect;
%mend;
%translate(EQ)

[Ksharp]

%str mask value in complie stage, %bquote mask value in execute stage.

compile stage is BEFORE execute stage.

Therefore BOTH worked.

[kisumsam]

Thanks for your response KSharp. I'm not sure if I followed tho. I thought the %str masks the value before it is resolved and it won't mask the resolved value. That's why we needed the bquote.

Below is an example that I read from another Sesug article:

%Let A = X,X ;
%Let B = Y%Str(&A)Y ;
%Put %Substr( %str(&B) , 4 , 1 );

In the third line, I'm masking &B with the %str function and it gives me error message:

56 %Let A = X,X ;

57 %Let B = Y%Str(&A)Y ;

58 %Put %Substr( %str(&B) , 4 , 1 );

ERROR: Macro function %SUBSTR has too many arguments.

I'm assuming this is because %str doesn't mask the resolved value which is YX,XY. The extra comma makes it an error in the %substr function.

Now, if I switch it to bquote which I believe masks the resolved value, it works:

%Let A = X,X ;
%Let B = Y%Str(&A)Y ;
%Put %Substr( %bquote(&B) , 4 , 1 );

Can I assume the %str doesn't mask the resolved value? If yes, the previous example:

%str(&var) shouldn't work because it doesn't mask the resolved value EQ. 

Can someone clarify on this? I'm confused...

[SAS_inquisitive · Accepted solution]

See this paper.

http://www2.sas.com/proceedings/sugi28/011-28.pdf

[kisumsam]

Thanks so much! I know this topic is complex and this paper explains the concept very well. Will probably have to re-read it a few times to fully understand macro quoting.

[ballardw]

From the documentation, %str masks

+ - * / < > = ¬ ^ ~ ; ,  # blank
AND OR NOT EQ NE LE LT GE GT IN

Note that you are using it with & so %str may not do what you want.

%NSTR does the same as %str but adds: & %

So perhaps you want %NSTR in this case.