Hi:
Is 9 the MONTH or the DAY???? September 1 or 9 January??? If 9 is the MONTH, then the INFORMAT for your function call (to convert from a character date to a numeric date) would be the MMDDYY informat.
If the 9 is the DAY and 1 is the MONTH then you would use a different INFORMAT, as shown in the other answer.
The explanation for WHY you need to convert is that SAS dates are represented as the number of days from a 0 date. SAS uses Jan 1, 1960 as the 0 date. So, for example, compare these calendar dates with their internally stored values.
[pre]
calendar date: | Nov 15, 1950 | Dec 31, 1959 | Jan 1, 1960 | Jan 2, 1960 | Nov 15, 1960
SAS date value: | -3334 | -1 | 0 | 1 | 319
[/pre]
When represented on a scale line this, SAS date values can be negative numbers and represent time all the way back to the start of the Gregorian calendar, as described here:
http://support.sas.com/documentation/cdl/en/basess/58133/HTML/default/a001397898.htm
...where it explains that:
" Note: SAS date values are valid for dates based on the Gregorian calendar from A.D. 1582 through A.D. 19,900. Use caution when working with historical dates. Although the Gregorian calendar was used throughout most of Europe from 1582, Great Britain and the American colonies did not adopt the calendar until 1752."
So when you have a text string that represents a date value, if you want to work with that variable, as a DATE value, in a SAS program or so you can use SAS formats or calculate time intervals, you have to convert the character string to a number using an INPUT function. When you convert a character variable or constant to a numeric variable, you need an INFORMAT that is appropriate for the conversion. In this case you would use an INFORMAT that would take your character string and convert it to the number of days since Jan 1, 1960.
Here are some more documentation links about working with SAS date values:
http://support.sas.com/documentation/cdl/en/basess/58133/HTML/default/a001397930.htm
http://support.sas.com/documentation/cdl/en/basess/58133/HTML/default/a001397901.htm
http://support.sas.com/documentation/cdl/en/basess/58133/HTML/default/a001397947.htm
cynthia