topic Re: Macro Programing using %local in SAS Programming

Macro Programing using %local

pchappus — Wed, 07 Nov 2018 19:05:12 GMT

I figured out a problem I had today because I had nested macros what used macro do loops which both start i=0. Because the inner macro went all the way to 70, when the outside macro referenced i for it's second pass, it thought i was 70 so it didn't need to do another loop.

My question is how to use %LOCAL to stop this.

When using the local statement, do I need to refer to that variable as &i or &j? Is %LET &j= the right syntax or should it be &j.= %EVAL(&i.+1);

Thanks!

%LOCAL i j;

%DO &i.=0 %TO 70;

%LET &j = %EVAL(&i.+1);

Re: Macro Programing using %local

tomrvincent — Wed, 07 Nov 2018 19:18:35 GMT

You should refer to either &i or &j depending on how they are used, since you've defined them both.

I would suggest naming local vars local_i and local_j so they are clearly defined. I don't think the '.' does anything, but I would remove it just in case.

Re: Macro Programing using %local

PaigeMiller — Wed, 07 Nov 2018 19:36:01 GMT

When using the local statement, do I need to refer to that variable as &i or &j? Is %LET &j= the right syntax or should it be &j.= %EVAL(&i.+1);

You wouldn't usually use %LET &J= ... ; in most cases the command is %LET J= ...;

None of the macro referencing changes because you define a macro variable to be local.

Re: Macro Programing using %local

Kurt_Bremser — Wed, 07 Nov 2018 19:46:08 GMT

All variables in a macro that are not macro parameters or explicitly meant to be global should be local, to avoid unwanted side effects.

Re: Macro Programing using %local

Peter_C — Wed, 07 Nov 2018 20:22:10 GMT

All local and outer vars would be available as if global to the "inner" macros unless "overridden" by the inner macro defining that name in a %local statement

Re: Macro Programing using %local

Astounding — Thu, 08 Nov 2018 01:23:51 GMT

What you have:

%LOCAL i j;

%DO &i.=0 %TO 70;

%LET &j = %EVAL(&i.+1);

What it should be:

%LOCAL i j;

%DO i=0 %TO 70;

%LET j = %EVAL(&i.+1);

The correct syntax for referring to a macro variable has nothing at all to do with whether the variable is local or global. %DO and %LET have the same syntax rules that apply to both local and global variables.

Where the %LOCAL statement belongs: within every macro definition that uses &i or &j. (There are a few, complex exceptions that you are not likely to encounter.)