topic Re: Macros in New SAS User

Macros

swayto — Wed, 05 Feb 2020 09:16:08 GMT

Question Output is 10 , why not 7?

%Macro mysum(n);
%if &n > 1 %then %eval(&n + %mysum(%eval(&n-1)));
%else &n;
%mend;

%put %mysum(4);

Re: Macros

Kurt_Bremser — Wed, 05 Feb 2020 09:22:26 GMT

4 + 3 + 2 + 1 = 10.

Re: Macros

ed_sas_member — Wed, 05 Feb 2020 09:24:54 GMT

Hi @swayto

You can use the mlogic option to display if the condition was evaluated as true or false:

options mlogic;

In the macro, you have nested conditions :

n = 4 so the first condition is true -> 4 + (as 3 is greater than 1, we apply the "if" condition so: 3 + (as 2 is greater than 1, we apply the "if" condition so: 2 + (as 1 is not greater than 1, we apply the 'else' condition so 1)

-> so 4 + 3 + 2+ 1

Hope it's clear.

Best,

Re: Macros

newfee — Wed, 05 Feb 2020 10:30:20 GMT

Do you want to have 7 as result? Or was it just that you wanted to have the code explained?

Re: Macros

Satish_Parida — Wed, 05 Feb 2020 11:07:52 GMT

/*Output 10 because of recursive code*/
%macro mysum(n);
	%if &n > 1 %then %eval(&n + %mysum(%eval(&n-1)));
	%else &n;
%mend;

options mprint mlogic;
%put %mysum(4);

/*Output 7 because of nonrecursive code*/
%macro mysum(n);
	%if &n > 1 %then %eval(&n + /*%mysum removed*/%eval(&n-1));
	%else &n;
%mend;

options mprint mlogic;
%put %mysum(4);

I hope this helped.