INTCK SAS function

[tSAS1]

I have the code below:

data want;
input mydate1 :yymmdd10. mydate2 :yymmdd10.;
format mydate1 mydate2 yymmddd10.;
datalines;

2020-08-27 2020-10-22
2020-03-01 2020-04-26
;
run;

data want2;
set want;
diff_months=intck("month",mydate1,mydate2);
diff_days=intck("day",mydate1,mydate2);
run;
proc print;run;

which provides the dataset want2

but I don't know why I don't have same diff_months=1 for both rows, since we have the same diff_days !

[PaigeMiller · Accepted solution]

In row one, the dates  cross two month boundaries. In row two, the dates cross one month boundary.

Perhaps you want to use the 'C' method of the INTCK function which then counts months from the starting date, rather than crossing a boundary.

diff_months=intck("month",mydate1,mydate2,'c');

[Reeza]

Because INTCK counts the number of interval boundaries that are crossed, not a calculation of number of months which actually doesn't have a unique definition. Would a month be like February, 28 or 29 days or like December with 31 days?  A 'month' doesn't have a standard definition so it's not a great unit of measure. 

From the doc:

Returns the number of interval boundaries of a given kind that lie between two dates, times, or datetime values.

So your first record starts in Month = 8 and ends in Month = 10 which is two boundaries crossed, 9 and 10.

In your second record, Month =3and ends in Month = 4 which is a single boundary crossed.

Some references for further details:

https://documentation.sas.com/doc/en/pgmsascdc/9.4_3.5/lefunctionsref/p1md4mx2crzfaqn14va8kt7qvfhr.h...

https://blogs.sas.com/content/iml/2017/05/15/intck-intnx-intervals-sas.html

Here's a great, but longer and in depth, reference for dates and times in SAS
https://communities.sas.com/t5/SAS-Communities-Library/Working-with-Dates-and-Times-in-SAS-Tutorial/...

---

@tSAS1 wrote:

I have the code below:

data want;
input mydate1 :yymmdd10. mydate2 :yymmdd10.;
format mydate1 mydate2 yymmddd10.;
datalines;

2020-08-27 2020-10-22
2020-03-01 2020-04-26
;
run;

data want2;
set want;
diff_months=intck("month",mydate1,mydate2);
diff_days=intck("day",mydate1,mydate2);
run;
proc print;run;

which provides the dataset want2

but I don't know why I don't have same diff_months=1 for both rows, since we have the same diff_days !

---