Language Reference

DO and END Statements

group statements as a unit

DO ;

           statements

END ;

The DO statement specifies that the statements following the DO statement be executed as a group until a matching END statement appears. DO statements often appear in IF-THEN/ELSE statements, where they designate groups of statements to be performed when the IF condition is true or false.

For example, consider the following statements:

  
    if x=y then 
       do; 
          i=i+l; 
          print x; 
       end; 
    print y;
 

The statements between the DO and END statements (called the DO group) are executed only if ; that is, they are executed only if all elements of are equal to the corresponding elements of . If any element of is not equal to the corresponding element of , the statements in the DO group are skipped and the next statement is executed. In this case, the next statement executed is as follows:

  
    print y;
 

DO groups can be nested; there is no limit imposed on the number of nested DO groups.

Here is an example of nested DO groups:

  
    if y>z then 
       do; 
          if z=0 then 
             do; 
                z=b*c; 
                x=2#y; 
             end; 
       end;
 

It is good practice to indent the statements in a DO group as shown in the preceding example so that their positions indicate their levels of nesting.