SAS invalid 'leap year' date issue yymmdd8

Question

I am reading in some raw data that has a couple of bad dates. Specifically, someone has keyed in "29th Feb" on a NON leap year. For example:

data _null_;
input test :yymmdd8.;
format test date9.;
cards;
20270229
run;

The customer would like this to revert to the 28th Feb. Is there a quick / efficient method of doing this? eg an equivalent of:

IF iserror(date) then date=date-1; ?

Any suggestions gratefully received!

Answer 1

I would be a bit more careful fixing dates. here is one way. hth.

%put sysvlong=&sysvlong sysscpl=&sysscpl;           
/* sysvlong=9.02.01M0P020508 sysscpl=W32_VSPRO */

/* read a date both as character(temp) and numeric(date).
   if the numeric date is missing then check if the
   character date ends with "0229," if so, then change it
   to "0228" and see if it is a valid date. 
   If OK, then that is it. otherwise, keep it missing. */
%let FEB29 = 0229; 
%let FEB28 = 0228;
data one;
  drop temp;
  input temp $char8. @1 date ?? yymmdd8.;
  if missing(date) then link fix;
  format date b8601da.;
  put (_all_) (=);
  return;
fix:
  if length(strip(temp))^=8 then return;
  if substr(temp,5) ^= "&FEB29" then return;
  date = input(cat(substr(temp,1,4), "&FEB28"), ?? yymmdd8.);
return;
cards;
20080229  ok
20090229  should be changed to 28th
201XX229  this should be missing
20110229  -> 28
20120229  ok 
20130229  -> 28
20270229  -> 28
;
run;

/* on log
temp=20080229 date=20080229
temp=20090229 date=20090228
temp=201XX229 date=.
temp=20110229 date=20110228
temp=20120229 date=20120229
temp=20130229 date=20130228
temp=20270229 date=20270228
NOTE: The data set WORK.ONE has 7 observations and 1 variables.
*/