help understanding MACRO functionality

[GeorgeBonanza]

The first macro below I got from SAS website.  I want to eliminate the %let start=, %let end=, and %let dif=, statements and just have the INTCK calculation done in the "%do i = 0 %to" line.  If I make substitutions one at a time, the code works fine up until I attempt to substitute "%let start =" piece.  If you try to run the code below, the first 3 will work but the last one will not. 

Please help me understand why the last code will not work.  Thanks in advance.

* THIS IS THE ORIGINAL FILE FROM THE SUPPORT.SAS WEBSITE;

%macro date_loop(start,end);
	%let start=%sysfunc(inputn(&start,anydtdte9.));
	%let end=%sysfunc(inputn(&end,anydtdte9.));
	%let dif=%sysfunc(intck(month,&start,&end));

	%do i=0 %to &dif;
		%let date=%sysfunc(intnx(month,&start,&i,b),date9.);
		%put &date;
	%end;
%mend date_loop;

%date_loop(01jul2015,01feb2016);

* THIS DOES THE &dif CALCULATION IN THE DO LOOP;

%macro date_loop(start,end);
	%let start=%sysfunc(inputn(&start,anydtdte9.));
	%let end=%sysfunc(inputn(&end,anydtdte9.));

	%do i=0 %to %sysfunc(intck(month,&start,&end));
		%let date=%sysfunc(intnx(month,&start,&i,b),date9.);
		%put &date;
	%end;
%mend date_loop;

* THIS SUBSTITUTES THE "%let end=" LINE INTO THE 3RD ARGUMENT OF THE INTCK FUNCTION;

%macro date_loop(start,end);
	%let start=%sysfunc(inputn(&start,anydtdte9.));

	%do i=0 %to %sysfunc(intck(month,&start,%sysfunc(inputn(&end,anydtdte9.))));
		%let date=%sysfunc(intnx(month,&start,&i,b),date9.);
		%put &date;
	%end;
%mend date_loop;

* THIS SUBSTITUTES THE "%let start=" LINE INTO THE 2RD ARGUMENT OF THE INTCK FUNCTION;

%macro date_loop(start,end);
	%do i=0 %to %sysfunc(intck(month,%sysfunc(inputn(&start,anydtdte9.)),%sysfunc(inputn(&end,anydtdte9.))));
		%let date=%sysfunc(intnx(month,&start,&i,b),date9.);
		%put &date;
	%end;
%mend date_loop;

[Shmuel]

I haven'ttest it but it seems to me that you should not enter %sysfunc within %sysfunc.

for example - instead line

%do i=0 %to %sysfunc(intck(month,&start,%sysfunc(inputn(&end,anydtdte9.))));

it should be:

%do i=0 %to %sysfunc(intck(month,&start,inputn(&end,anydtdte9.)));

[LaurieF · Accepted solution]

But - but - in your intnx function in the %let within the %do loop - you're passing in 01jul2015, not 20270. You have to convert it somewhere! 

I have never, ever, made this mistake mistake. Oh, no, no, no, no, no… 

BTW, you can convert dates like that on the fly with %sysevalf, funnily enough.

%let date=%sysfunc(intnx(month, %sysevalf("&start"d) ,&i,b),date9.);

or even simply

%let date=%sysfunc(intnx(month, "&start"d ,&i,b),date9.);

[GeorgeBonanza]

I thought it was erroring out in the do loop.  you are correct, that was a dumb error, glad you never made a similar mistake.

[LaurieF]

Just not today! But tomorrow I probably will.

[LaurieF]

No, multiple %sysfuncs are fine. It can make it hard to read, but it does work very well.

[art297]

Your last macro will work if written like @LaurieF suggested:

%macro date_loop(start,end);
%do i=0 %to %sysfunc(intck(month,%sysevalf("&start"d),%sysevalf("&end"d)));
%let date=%sysfunc(intnx(month,%sysevalf("&start"d),&i,b),date9.);
%put &date;
%end;
%mend date_loop;
%date_loop(01jul2015,01feb2016)

HTH,

Art, CEO, AnalystFinder.com

[LaurieF]

Simplify, simplify, simplify:

%macro date_loop(start,end);
	%do i = 0 %to %sysfunc(intck(month, "&start"d, "&end"d));
		%let date = %sysfunc(intnx(month,"&start"d, &i, b), date9.);
		%put &date;
	%end;
%mend date_loop;

%date_loop(01jul2015, 01feb2016);