topic Re: What is the purpose of rc if it’s never checked? in SAS Programming

What is the purpose of rc if it’s never checked?

PopCorn14 — Thu, 12 Aug 2021 22:39:52 GMT

Hi,

Many times, I see in code that we assign a value to a return code variable like rc (see examples below) however that rc variable is never checked down the road.

Examples:

rc=filename ("fdir","&path");

%let rc=%sysfunc(grdsvc_enable(_all_,resource=SASApp));

Can someone explain to me the purpose of assigning rc if we do not check its value to continue? I would expect something like this below but it is never the case.

If rc>0 then…..continue

Else …

Thank you.

Re: What is the purpose of rc if it’s never checked?

SASKiwi — Thu, 12 Aug 2021 22:55:17 GMT

Checking the return code is optional but I would regard it as a best practice check if following processing relies on it being successful. Not doing it is an example of lazy and potentially unreliable programming practices.

Personally I always check these if required and I've seen a lot of code examples done by others also doing this.

Re: What is the purpose of rc if it’s never checked?

jimbarbour — Thu, 12 Aug 2021 23:12:05 GMT

There are a lot of RC's in SAS. The RC's from functions, well, some matter more than others. The ones from a hash lookup, a FIND() in other words, I always check. If you're doing direct file reading FOPEN, etc., checking the RC is definitely best practice.

I also routinely check other RC's, the ones returned from Data an Procedure steps, via a macro and write them to my log at the end of a run. I find this extremely helpful.

       +-----------------------------------------------------------------------------------------------------------------+
       | Return codes and Sys messages as of 2021/08/12 18:09:23.73
       | SYSERR             =  0
       | SYSCC              =  0
       | SYsrc=0
       | SYSFILRC           =  1
       | SYSLIBRC           =  0
       | SYSLCKRC           =  0
       | SQLEXITCODE        =  0
       | SQLRC              =  0
       | SQLXRC             =  0
       | ReturnCode         =  0
       | Abort              =  0
       | SysErrorText       =     
       | Save_ErrorText     =     
       | SysWarningText txt =    
       | Save_WarningText   =    
       +-----------------------------------------------------------------------------------------------------------------+

Jim

Re: What is the purpose of rc if it’s never checked?

ballardw — Fri, 13 Aug 2021 00:48:20 GMT

In some cases the function call may be confused with something else.

One example:

433  data _null_;
434    filename('somefile',"D:\Users\Owner\DATA\Super\examples.csv");
                                                                    -
                                                                    22
                                                                    76
ERROR: Undeclared array referenced: filename.
ERROR 22-322: Syntax error, expecting one of the following: +, =.

ERROR 76-322: Syntax error, statement will be ignored.

435  run;

NOTE: The SAS System stopped processing this step because of errors.
NOTE: DATA statement used (Total process time):
      real time           0.00 seconds
      cpu time            0.00 seconds


436
437  data _null_;
438    rc=filename('somefile',"D:\Users\Owner\DATA\Super\examples.csv");
439  run;

In the case of FILENAME you do have a statement of the same name with different syntax. So the compiler expects certain elements depending on the syntax attempted and if you use a call that looks like the function then it expects a target variable to assign the code to for success or not.

Re: What is the purpose of rc if it’s never checked?

Kurt_Bremser — Fri, 13 Aug 2021 05:22:39 GMT

The result of the FILENAME function is often not checked because the next step is a call to the FOPEN or DOPEN function, and that will fail if the FILENAME did not work, so the check there covers both:

rc = filename(fref,path);
fid = fopen(fref);
if fid then ....

Re: What is the purpose of rc if it’s never checked?

PopCorn14 — Wed, 18 Aug 2021 03:20:51 GMT

Thank you very much @ballardw. I selected your answer for ACCEPTED SOLUTION but not sure what happened. I will try to correct that.

Your answer made a lot of sense and was well illustrated with your example.

Re: What is the purpose of rc if it’s never checked?

PopCorn14 — Wed, 18 Aug 2021 02:52:50 GMT

Thank you @jimbarbour for the list of all the return codes.

Re: What is the purpose of rc if it’s never checked?

PopCorn14 — Wed, 18 Aug 2021 02:54:39 GMT

Thank you @Kurt_Bremser for your explanation.

Re: What is the purpose of rc if it’s never checked?

PopCorn14 — Wed, 18 Aug 2021 02:56:27 GMT

Thank you @ballardw for your great help. ACCEPTED SOLUTION (I need to correct that).

Re: What is the purpose of rc if it’s never checked?

PopCorn14 — Wed, 18 Aug 2021 02:57:23 GMT

Thank you @SASKiwi for your reply.