比较SAS中的日期（日期1 =日期2）

I have two dates in my SAS dataset that I would like to compare i.e., does date1 = date2. I attempted to do this using the ifn and ifc functions but have a suspicion they are not working correctly. I took this code directly from a sugi, but have worked with these functions successfully comparing character/numeric variables. I also successfully attempted the comparison using proc sql, but I want to learn to do this in a data step. I have two dates in my SAS dataset that I would