What is difference "?" using in PUT & INPUT function

[RajasekharReddy]

Hello ,

I am using PUT & INPUT function so long and using below like

xx=put(aa,?best.)

zz=input(bb,??best.)

May i know why we are using "?" in put & input function and what is difference with out "?" and with "?"

Thank you in advance.

[PaigeMiller]

https://v8doc.sas.com/sashtml/lgref/z0180357.htm

[PeterClemmensen]

The INPUT Function Documentation says:

? or ??

specifies the optional question mark (?) and double question mark (??) modifiers that suppress the printing of notes and input lines when invalid data values are read. The ? modifier suppresses the invalid data message. The ?? modifier suppresses the invalid data message and prevents the automatic variable _ERROR_ from being set to 1 when invalid data is read.

[ballardw]

An example use case: Data being read has a date field in mm/dd/yyyy format but missing values where the data was not recorded are represented by 99/99/9999.

Since you know that values will be invalid dates and actually represent missing data when the values are read you will be okay with SAS variables with missing values but you may not want to wade through a bunch of junk in the log for a know data issue. So a data step to read the example data uses the ?? modifier as follows:

data example;
   input x ??mmddyy10.;
   format x mmddyy10.;
datalines;
01/01/2019
99/99/9999
;
run;

remove the ?? and replace with either a single ? or nothing to see the different behaviors.

Reading a field that should be numeric but sometimes has NA or other not entered or not available code would be another similar use.