In SAS, the switch statement is called a SELECT statement.
When a select expression is given, it evaluates this and does a relative jump, which is similar to the optimization done by a C or Java compiler in a switch statement. It doesn’t have any fall-throughs though, so it’s more like Ruby. It looks like this:
select(i); when(0) put 'none'; when(1) put 'one'; when(2) put 'a couple'; when(3,4,5) put 'a bunch'; otherwise put 'a lot'; end;
In SAS there’s a second mode for using it, where the expression after SELECT
is left out. The closest similarity to another language I know of is
PHP’s switch with
switch(true) and using cases with conditions, however PHP’s
version still has fall-through. Doing this in SAS looks like this:
select; when(i<5) put 'lt 5'; when(i=5) put 'eq 5'; when(i>5) put 'gt 5'; otherwise put 'math is broken'; end;
The statement is basically
syntactic sugar to
make your code easier to read, and is logically no different from a chain of
statements. The statement will break out after the first statement evaluates
true, even if statements further down would also evaluate true. It isn’t any
if(i<5) then put 'lt 5'; else if(i=5) then put 'eq 5'; else if(i>5) then put 'gt 5'; else put 'math is broken';
- Statements can be reordered and/or dynamically inserted through SAS’s macro preprocessor runs without having to worry about if it needs an “if” or an “else if”.
- For OCD-types, the formatting can look prettier.
- For golfers, it uses fewer keystrokes.