> From: Ace [mailto:b.rogers@VIRGIN.NET] > Found a wierd 'undocumented feature' in SAS - reapeating the word > 'else' dont't generate any error or even warning statements. > > data; > if 1 = 2 then x = 33; > else else else x=44 ; > put x ; > run; > > runs absolutely fine in V6 & 8, windows & unix.

for the record runs in v9, too.

see also the recommended optimization: SAS Programming tips:a Guide to Efficient SAS Processing Tip 5.13: Use a series of conditions 'When a statement contains a large number of conditions, use a series of IF-THEN clauses rather than a compound expression with AND.'

AND: evaluates all conditions even if one is false IF-THEN: stops evaluating the series as soon as one clause is false, thus saving evaluation thru the rest of the series. which will save those ever so valuable CPU cycles, especially on many test, and many obs.

data _NULL_; infile cards; input X Y; if X=1 and y=2 then put 'and ' X= Y=; else put 'else: and ' X= Y=;

if X=1 then if Y=3 then put 'double if ' X= Y=; else put 'else: double if ' X= Y=; put '- - - -'; cards; 1 2 1 3 1 4 ;run;

* SQL stops evaluating either of the above constructs when it meets the first false condition.

Ron Fehd the macro maven CDC Atlanta GA USA RJF2@cdc.gov

OpSys: Win_Pro Ver: 9.000000000

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