INTCK() counts the number of interval boundaries crossed. If you are counting WEEKDAYs then Saturday and Sunday don't count.
Fortunately you have a programming language at your fingertips you can use to see what it is doing.
Let's look at 7 days in March 2020, since it happens to start with the first day on a Sunday, which is the first day of the week.
data check;
do from='01MAR2020'd to '07MAR2020'd;
do days=0 to 8;
to=from+days;
weekdays = intck('weekday',from,to);
put from downame. '->' to downame. days 3. weekdays 3. ;
output;
end;
put;
end;
format from to date9. ;
run;
Results:
Sunday-> Sunday 0 0
Sunday-> Monday 1 1
Sunday-> Tuesday 2 2
Sunday->Wednesday 3 3
Sunday-> Thursday 4 4
Sunday-> Friday 5 5
Sunday-> Saturday 6 5
Sunday-> Sunday 7 5
Sunday-> Monday 8 6
Monday-> Monday 0 0
Monday-> Tuesday 1 1
Monday->Wednesday 2 2
Monday-> Thursday 3 3
Monday-> Friday 4 4
Monday-> Saturday 5 4
Monday-> Sunday 6 4
Monday-> Monday 7 5
Monday-> Tuesday 8 6
Tuesday-> Tuesday 0 0
Tuesday->Wednesday 1 1
Tuesday-> Thursday 2 2
Tuesday-> Friday 3 3
Tuesday-> Saturday 4 3
Tuesday-> Sunday 5 3
Tuesday-> Monday 6 4
Tuesday-> Tuesday 7 5
Tuesday->Wednesday 8 6
Wednesday->Wednesday 0 0
Wednesday-> Thursday 1 1
Wednesday-> Friday 2 2
Wednesday-> Saturday 3 2
Wednesday-> Sunday 4 2
Wednesday-> Monday 5 3
Wednesday-> Tuesday 6 4
Wednesday->Wednesday 7 5
Wednesday-> Thursday 8 6
Thursday-> Thursday 0 0
Thursday-> Friday 1 1
Thursday-> Saturday 2 1
Thursday-> Sunday 3 1
Thursday-> Monday 4 2
Thursday-> Tuesday 5 3
Thursday->Wednesday 6 4
Thursday-> Thursday 7 5
Thursday-> Friday 8 6
Friday-> Friday 0 0
Friday-> Saturday 1 0
Friday-> Sunday 2 0
Friday-> Monday 3 1
Friday-> Tuesday 4 2
Friday->Wednesday 5 3
Friday-> Thursday 6 4
Friday-> Friday 7 5
Friday-> Saturday 8 5
Saturday-> Saturday 0 0
Saturday-> Sunday 1 0
Saturday-> Monday 2 1
Saturday-> Tuesday 3 2
Saturday->Wednesday 4 3
Saturday-> Thursday 5 4
Saturday-> Friday 6 5
Saturday-> Saturday 7 5
Saturday-> Sunday 8 5
Which counts would you want to be different?
Perhaps you want count the number of weekdays between FROM and TO, inclusive? If so then see what you get if you use this formula instead:
intck('weekday',from-1,to)
Are these weekday counts what you want?
Sunday-> Sunday 0 0
Sunday-> Monday 1 1
Sunday-> Tuesday 2 2
Sunday->Wednesday 3 3
Sunday-> Thursday 4 4
Sunday-> Friday 5 5
Sunday-> Saturday 6 5
Sunday-> Sunday 7 5
Sunday-> Monday 8 6
Monday-> Monday 0 1
Monday-> Tuesday 1 2
Monday->Wednesday 2 3
Monday-> Thursday 3 4
Monday-> Friday 4 5
Monday-> Saturday 5 5
Monday-> Sunday 6 5
Monday-> Monday 7 6
Monday-> Tuesday 8 7
Tuesday-> Tuesday 0 1
Tuesday->Wednesday 1 2
Tuesday-> Thursday 2 3
Tuesday-> Friday 3 4
Tuesday-> Saturday 4 4
Tuesday-> Sunday 5 4
Tuesday-> Monday 6 5
Tuesday-> Tuesday 7 6
Tuesday->Wednesday 8 7
Wednesday->Wednesday 0 1
Wednesday-> Thursday 1 2
Wednesday-> Friday 2 3
Wednesday-> Saturday 3 3
Wednesday-> Sunday 4 3
Wednesday-> Monday 5 4
Wednesday-> Tuesday 6 5
Wednesday->Wednesday 7 6
Wednesday-> Thursday 8 7
Thursday-> Thursday 0 1
Thursday-> Friday 1 2
Thursday-> Saturday 2 2
Thursday-> Sunday 3 2
Thursday-> Monday 4 3
Thursday-> Tuesday 5 4
Thursday->Wednesday 6 5
Thursday-> Thursday 7 6
Thursday-> Friday 8 7
Friday-> Friday 0 1
Friday-> Saturday 1 1
Friday-> Sunday 2 1
Friday-> Monday 3 2
Friday-> Tuesday 4 3
Friday->Wednesday 5 4
Friday-> Thursday 6 5
Friday-> Friday 7 6
Friday-> Saturday 8 6
Saturday-> Saturday 0 0
Saturday-> Sunday 1 0
Saturday-> Monday 2 1
Saturday-> Tuesday 3 2
Saturday->Wednesday 4 3
Saturday-> Thursday 5 4
Saturday-> Friday 6 5
Saturday-> Saturday 7 5
Saturday-> Sunday 8 5
... View more
