topic Understanding code in SAS Programming

Understanding code

kaushal2040 — Tue, 27 Jan 2015 20:06:19 GMT

Hello Forum,

I the following code, "if 0 then" do?

Thanks.

data base;

if 0 then modify base;

set one two e04 open=defer;

output;

run;

Re: Understanding code

ballardw — Tue, 27 Jan 2015 20:12:22 GMT

0 is treated by SAS in logical comparisons as FALSE. So basically the code says not to do anything as the part following THEN only executes when the comparison is true.

This may be a programmer holding bit for testing other logic or does not know the conditions that will be needed but knows the conditional part will be needed later.

Re: Understanding code

kaushal2040 — Tue, 27 Jan 2015 21:39:01 GMT

Thanks ballardw,

So the code says do not modify the base data set? I was wondering what " but knows the conditional part will be needed later'" mean in your last sentence.

Re: Understanding code

ballardw — Tue, 27 Jan 2015 22:04:43 GMT

Suppose I am writing code per some directions from the boss and he says "We'll need to modify this table but the conditions wont' be set until the meeting next week." I know that I'll have to provide for handling that condition, which could be quite complex, but I don't know what it is at the time I start coding the pieces I do have requirements for. I put the stub of code you're asking about as a reminder of where in the process I need to implement that condition.

Re: Understanding code

Tom — Tue, 27 Jan 2015 22:10:43 GMT

The program basically appends datasets ONE TWO and E04 to the end of the dataset BASE.

The "IF 0 THEN" does absolutely nothing in this case. If you remove it and just have the MODIFY statement the code runs the same.

This construct is sometimes used with a SET statement instead of a MODIFY statement. The effect then is that the compiler sees the SET statement and adds the variables in the referenced data set to the data vector but the IF 0 THEN causes the SET statement to never execute. It is a quick way to make sure your new dataset has the same variables.