SAS Certification Prep Guide, 5th Edition

Nesting DO Loops

Indenting and Nesting DO Groups

You can nest DO groups to any level, just like you nest IF-THEN/ELSE statements.

Note: The memory capabilities of your system might limit the number of nested DO statements that you can use.

Here is an example structure of nested DO groups:

do;
	...more SAS statements...;
		do;
			...more SAS statements...;
				do;
					...more SAS statements...;
				end;
		end;
end;

Tip

It is good practice to indent the statements in DO groups, as shown in the preceding statements, so that their position indicates the levels of nesting.

Examples: Nesting DO Loops

Iterative DO statements can be executed within a DO loop. Putting a DO loop within a DO loop is called nesting.

do i=1 to 20; 
   ...more SAS statements... 
   do j=1 ...