Question of using %str macro when pass macro parameter

[Henry]

Dear SAS experts,

I use SAS for many years, but recently I meet following issue related to %str and cannot explain. Please see my SAS codes below:

data abc_101;

a=3;

run;

%macro test1(id= );

%put abc_&id.;

data a;

set abc_&id.;

run;

%mend test1;

%test1(id=%str(101));

MLOGIC(TEST1): Beginning execution.
MLOGIC(TEST1): Parameter ID has value
101
MLOGIC(TEST1): %PUT abc_&id.
abc_101
MPRINT(TEST1): data a;
MPRINT(TEST1): set abc_101;
ERROR: File WORK.ABC_.DATA does not exist.
MPRINT(TEST1): run;

SAS log shows error that no WORK.ABC_.DATA found. It seems like there is a blank in the front of &id which cause SAS cannot find ABC_ data. Why %put statement shows correct string, but set statement cannot. I also tried different solutions below:

%macro test2(id= );

%let id=%trim(&id);

%put abc_&id.;

data a;

set abc_&id.;

run;

%mend test2;

%test2(id=%str(101));

%macro test3(id= );

%put abc_&id.;

data a;

set abc_&id.;

run;

%mend test3;

%test3(id=101);

Both works. I use %str function all the time to pass macro parameters, but now I am kind of confused. Does any experts can help me explain why we need to use %trim in the macro program or not use %str function. Thank you so much. 

[Tom · Accepted solution]

The macro quoting is confusing the SAS parser into seeing multiple tokens instead of one token.

You can add an call to the %unquote() macro function.

set %unquote(abc_&id.);

Or perhaps easier you can build the name first and then use it.

%let dsname=abc_&id.;
set &dsname. ;

[PaigeMiller]

The string 101 does not need to be enclosed by %STR()

%STR() is only needed for certain special characters, as stated in the documentation.

[Quentin]

Tom already gave the correct answer: you need to %unquote() it.

Just to add, I believe this is a bug (though I'm not sure SAS views it as such).  The value should be %unquoted automatically before it causes problems, but it doesn't always happen.  The rule I learned is that if you turn on MPRINT, and the code in the log looks valid while generating an error, try %UNQUOTE.  The SAS docs mention this:

https://documentation.sas.com/?docsetId=mcrolref&docsetTarget=p1f5qisx8mv9ygn1dikmgba1lmmu.htm&docse...

What to Do When Automatic Unquoting Does Not Work

... In rare cases, masking text with a macro quoting function changes how the word scanner tokenizes the text. (The word scanner and tokenization are discussed in SAS Programs and Macro Processing and and Macro Processing.) For example, a single or double quotation mark produced by resolution within the %BQUOTE function becomes a separate token. The word scanner does not use it as the boundary of a literal token in the input stack. If generated text that was once masked by the %BQUOTE function looks correct but SAS does not accept it, you might need to use the %UNQUOTE function to restore normal tokenization. (emphasis added)

When you use %TRIM the code works because %TRIM unquotes it.  As would %UPCASE, or other macro functions that don't explicitly quote the value they return.