topic Re: How to identify an extra semicolon in SAS Programming

How to identify an extra semicolon

AndersS — Sat, 01 Jun 2013 16:50:38 GMT

Hi! If I write IF A < B then; B= A; etc. B will always be given the value of A - because there is a semicolon directly after THEN.

In other words - SAS does not give any protest or WARNING when the THEN Clause is empty!

My Question: Is there any good way of identifying this problem ?

(except using the Editor and look for the strings "THEN;" and "THEN ;" )

Br Anders

Re: How to identify an extra semicolon

Tom — Sat, 01 Jun 2013 17:00:11 GMT

A lot of SAS programmers adopt a programming style of only one statement per line. So then seeing more than one semi-colon on the same line would be a warning that there might be an issue.

Re: How to identify an extra semicolon

AndersS — Sat, 01 Jun 2013 17:27:14 GMT

Hi! I do agree with Tom, but:

IF A < B THEN;

B= A;

- only one semicolon . Still no warning from SAS.

I have been using SAS for many years. I have never made this mistake before, until yesterday.

In my 'program' this a statement that can be taken away.

I think that this is a bug in SAS.

Re: How to identify an extra semicolon

AndersS — Sat, 01 Jun 2013 18:10:00 GMT

Hi!
I tried the same problem in SAS MACRO:

%MACRO TEST(A);

%IF &A=2 %THEN %PUT OK&A;

%MEND TEST;

%TEST(2);

%MACRO TESTTHEN(A);

%IF &A=3 %THEN;

%PUT OK&A;

%MEND TESTTHEN;

%TESTTHEN(3);

I think that this is a bug in SAS Macro.

Question: Are there any good ways to identify an extra semicolon ?

Re: How to identify an extra semicolon

TomKari — Sat, 01 Jun 2013 19:18:11 GMT

I appreciate your point, but I disagree with you.

IF A < B THEN;

is a perfectly valid statement. It means don't do anything if A is less than B. Of course, for it to be useful it would have to be followed by an ELSE, as in

IF A < B THEN; ELSE COMMENT = "A is not less than B";

which of course is equivalent to

IF A >= B THEN; ELSE COMMENT = "A is not less than B";

and it's a sensible response to say that the latter should always be used. However, there are a couple of circumstances where these "no-op" statements occur:

Fairly often, one ends up in a nested set of IF statements, such as

IF A = 1

THEN IF B = 1

THEN X = 5;

ELSE;

ELSE X = 6:

where the ELSE; is required to match ELSE X = 6 with IF A = 1.

Another case is where the condition could be:

IF A = 1 THEN X = 5;

without an ELSE clause, but for reasons of clarity and readability it makes more sense to code the condition as the negation, so it becomes

IF /* a condition that makes the most sense stated this way */ THEN;

ELSE /* some actions */;

I know it sounds weird, but I've done it.

My $.02 worth!

Tom