topic Re: if-else in SAS Programming

if-else

pchen002 — Wed, 27 Sep 2017 07:15:44 GMT

The following SAS program is submitted:

data work.new;
length word $7;
amount = 4;
it amount = 4 then word = ‘FOUR’;
else if amount = 7
then word = ‘SEVEN’;
else word = ‘NONE!!!’;
amount = 7;
run;
What are the values of the AMOUNT and WORD variables in SAS dataset work.new?

A. amount word
4 FOUR

B. amount word
4 NONE!!!

C. amount word
7 FOUR

D. amount word
7 SEVEN

The answer is C, I do not quite understand why.

Re: if-else

Kurt_Bremser — Wed, 27 Sep 2017 07:38:07 GMT

The if condition is evaluated before amount is set to 7.

Keep in mind that the data step is a pure procedural programming language, where things happen in sequence.

Re: if-else

ShiroAmada — Wed, 27 Sep 2017 07:39:14 GMT

Its the sequence of the statements.

1. First sas read amount=4

2. Next SAS read and executed your first if statement (amount=4). Given that the condition has been satisfied the assingment statement was executed.

3. Lastly, sas encountered another assignment statement that overwrites the previous value (amount=4) and set it to 7.

Re: if-else

gamotte — Wed, 27 Sep 2017 07:42:08 GMT

Hello,

amount is first set to 4 with the instruction

amount=4;

Then word is set to 'FOUR' with the instruction

it amount = 4 then word = ‘FOUR’;

lines begining by else can be ignored because the first if condition was met.

The last instruction before run sets amount to 7.

So in the end amount=7 and word='FOUR' (answer C)

Re: if-else

Shmuel — Wed, 27 Sep 2017 07:43:27 GMT

Put yourself being a computer, do each staement in the order it is written and

fill next table:

line staement amount word

=== ======= ====== ========

1 data work.new; . ' '

2 length word $7; . ' '

3 amount = 4; 4 ' '

4 it amount = 4 then word = ‘FOUR’; 4 'Four'

5 else if amount = 7; 4 'Four' /* no change */

Continue to fill it with rest of lines. You will get the answer to your question.