sas macro code to check missing dates

Question

If the input date is given below then the date output should be as given

I want sas macro code to check missing date in the inputs

    1.-MMM-YYYY = 01-MMM-YYYY
    --YYYY    = 01-JAN-YYYY 
    DD--YYYY  = DD-JAN-YYYY 
    DD-MMM-   = DD-MMM-0000

Answer 1

I created a dataset with all possible situations of missing day, month and year. The datasteps below address all possibilities and how to handle them to create the result variable new_bdate in the format you requested.

data have; 
  input birthdate $20.; 
   datalines4;
  -JAN-1975 
  --1977 
  02--1978 
  03-JAN- 
  01-JAN-1980
  03--
  -JAN-
;;;;
run;

data haha2(Keep = birthdate new_bdate);
  set have;  
   format day $2. month $3. Year $4. New_bdate $11.;
   call scan(birthdate, 1, First_Pos, First_Length);
   First_Word = substrn(birthdate, First_Pos, First_Length);
   call scan(birthdate, -1, Last_Pos, Last_Length);
   Last_Word = substrn(birthdate, Last_Pos, Last_Length);
   if length(birthdate) = 11 then length1 = 'Y';
  else length1 = 'N';

   if length1 = 'Y' then do;
      Day = substr(birthdate,1,2);
      Month = substr(birthdate,4,3);
      Year = substr(birthdate,8,4);
   end;
   else if length1 = 'N' then do;
     if (First_Pos = '1' and Last_Length = '2')  then do 
              Day = First_Word;
              Month = 'JAN';
              Year = '0000';
        end;
      else if (First_Pos = '1' and Last_Length = '3')  then do 
              Day = First_Word;
              Month = Last_Word;
              Year = '0000';
        end;
     else if (First_Pos = '1' and Last_Length = '4')  then do 
              Day = First_Word;
              Month = 'JAN';
              Year = Last_Word;
        end;
   if (First_Pos = '2' and Last_Length = '3')  then do 
              Day = '01';
              Month = First_Word;
              Year = '0000';
        end;
      else if (First_Pos = '2' and Last_Length = '4')  then do 
              Day = '01';
              Month = First_Word;
              Year = Last_Word;
        end;
     else if (First_Pos = '3' and Last_Length = '4')  then do 
              Day = '01';
              Month = 'JAN';
              Year = Last_Word;
        end;
    end;
New_bdate = Day||'-'||Month||'-'||Year;
run;