dates on sas

[saza]

I am stuck trying to format dates on sas and cant figure out what i'm doing wrong?

Was asked, 

1. Using DEMOMED, perform the following tasks in a new temporary dataset called TEMP1: 
1. Calculate each person’s age as of the date of registration (REG_DATE) using the birth date (BDATE). The age should be an integer value and have the variable name AGE.
2. Create a new variable called TIMEFUP that is equal to the total amount of time between the date of the registration and June 30, 2008. The value should be in years (decimals are ok). 
3. You have determined that values of WEIGHTKG greater than the 99th percentile (131 kg) and those less than the 1st percentile (14.5 kg) are data entry errors. Set the weights for subjects with values outside of these limits equal to missing. 
4. Use the HEIGHTCM and WEIGHTKG variables to calculate BMI for each person (100 centimeters = 1 meter). Run a procedure that will let you make sure BMI was calculated correctly.
   
   I recall being able to do all of this in one code but I cannot get the first part to work so that I can continue. this is my code for number 1
   

   data age;
       set demomed;
       reg_date = input(reg_date,MMDDYY10.);
       format reg_date MMDDYY10.;
   run;
   data age; 
   set demomed; 
   age = yrdif(reg_date,bdate);
   run; 

[Kurt_Bremser]

Maxim 3: Know Your Data.

Is reg_date character, or numeric with a MMDDYY10. format assigned?

[saza]

Reg_date is the registration date for each patient. So I believe numeric variable

[Kurt_Bremser · Accepted solution]

Do not believe. Know.

Inspect the properties of the variable in the dataset viewer, or run a PROC CONTENTS on the dataset.

[saza]

Sorry, it is a numeric variable