invalid numeric data error in date

[alexdsa310]

I have start and stop date in  2016-02-11 and 2016-02-24 formats and i am doing the below code:

data trt1;
set trt;
exp = (SEENDTC-SESTDTC+1);
run;

But i get the below error message and i even tried to give format statement but still its not working. any help?

NOTE: Invalid numeric data, SEENDTC='2016-02-24' , at line 161 column 11.
NOTE: Invalid numeric data, SESTDTC='2016-02-11' , at line 161 column 19.

[Kurt_Bremser · Accepted solution]

This is because you do not have a SAS date value, but a string containing a human-readable date.

First convert to a SAS date value:

data trt1;
set trt;
format SEENDTC_num SESTDTC_num yymmddd10.;
SEENDTC_num = input(SEENDTC,yymmdd10.);
SESTDTC_num = input(SESTDTC,yymmdd10.);
exp = (SEENDTC_num - SESTDTC_num + 1);
run;