Handbook of SAS DATA Step Programming

66 Handbook of SAS

®

DATA Step Programming

FIGURE 5.2

The last three iterations of the DO loop in Program 5.4.

67Writing Loops in the DATA Step

In the DO WHILE loop, the expression is evaluated at the top of the DO

loop. The DO loop will not execute if the expression is false. We can rewrite

program5.4 by using the DO WHILE loop.

Program 5.5:

data ex5_5(drop = rannum);

do while (id < 4);

id + 1;

rannum = ranuni(2);

if rannum > 0.5 then group = 'D';

else group = 'P';

output;

end;

run;

In Program 5.5, the ID variable is created inside the loop with the SUM

statement. Thus, the variable ID is initialized to 0 in the PDV at the begin-

ni