Dynamically change the variable attributes

[SAS_inquisitive]

This macro code creates the code below. I want to create only one length statement and only variable names changing dynamically.

data test;
input var1 $ var2 $;
cards;
 1 4
 2 5
 3 6
 ;

%macro m;

	data test;
		%do i= 1 %to 2;
			length var&i $ 10.;
		%end;

		set test;
	run;

%mend m;

%m

/* cod generated */

data test;
	length var1 $ 10.;
	length var2 $ 10.;
	set test;
run;

/* desired code */

data test;
	length var1 $ 10.
           var2 $ 10.;
	set test;
run;

[data_null__]

Just move the word LENGTH before %DO and semi-colon after %end;

[data_null__]

Or how about just do
length var1-var2 $10;

[Astounding · Accepted solution]

Definitely a worthwhile technique to learn!

Here's what you have now:

%do i=1 %to 2;

   length var&i $ 10.;

%end;

Here's what the replacement would look like (notice the dot is not required when defining length, only for formats):

length

%do i=1 %to 2;

   var&i

%end;

$ 10;

Good luck.

[SAS_inquisitive]

@data_null__ @Astounding.  Thank you. May be I could start another thread. What if  variables are not var1 and var2 (ie. can not referenced by macro variable &i) such as x and y and I need to change  their attributes inside macro definition.

data test;
input x $ y $;
cards;
 1 4
 2 5
 3 6
 ;

[Astounding]

The answer depends on how the variable names are stored.  For example, do you have a macro variable holding a list of variable names:

%let var_list = x var1 y;

Do you have a data set where a DATA step variable takes on values of "x" "var1" and "y"?

How do you expect to provide the list of variable names?

[SAS_inquisitive]

@ Astounding. Yes, the horizontal list as you mentioned.
%let var_list=x y;

[Astounding]

When you already have all the variable names assembled in a single macro variable, I would skip the looping:

length &var_list $ 10;