resetting temporary variable in merge statement

[SAS_inquisitive]

What is the purpose of resetting temporary variables many1 and many2 in following code. 

data pairs oddballs;
	many1=0;
	many2=0;
	merge many1 ( in = many1 )
		many2 ( in = many2 );
	by partkey;

	if many1 and many2 then
		output pairs;
	else output oddballs;
run;

[ballardw]

No practical purpose served that I can tell. If you found this code somewhere the assignments might be an artifact left in from previous code tested.

Or someone misunderstanding how temporary variables work in SAS.

[Astounding · Accepted solution]

This type of code is used for many-to-many matches.  For example, let's say:

• MANY1 contains 3 observations per PARTKEY
• MANY2 contains 5 observations per PARTKEY
• The objective is to output 3 observations per PARTKEY, matching the first from MANY1 with the first from MANY2, the second from MANY1 with the second from MANY2, etc.  Discard any that are left over from the data set containing more observations.

That's what this program accomplishes ... matching based on whichever data set has fewer observations, and putting those matched observations into PAIRS.  Discarding any that are left over without a match, putting them into ODDBALLS.