what is %sysfunc(open()) : a 0/1 answer or sth else

[stataq]

Hello,

I have a question on %sysfunc(open())

I thought  %sysfunc(open()) is open a dataset, which give 0 or 1 to show whether the dataset is opened successfully.  I accidentally forgot to close the file, and found that if I keep running following code, &_dsid is not a 0,1  value, instead it will keep going up to 2, 3, 4.

Can anyone explain what  _dsid really is? 

and also what varnum(1, &_colvar) is. why 1 instead of not a dataset name here?

%let _dsid=%sysfunc(open(sashelp.baseball));
%put &_dsid;
%let _colvar=team;
%let _varnum=%sysfunc(varnum(&_dsid,&_colvar));
%put &_varnum;

Thanks.

[Kurt_Bremser]

Maxim 1: Read the Documentation.

From OPEN Function

The OPEN function opens a SAS data set, DATA step, or a SAS SQL view and returns a unique numeric data set identifier, which is used in most other data set access functions. OPEN returns 0 if the data set could not be opened.

[Tom]

If you want to know what %SYSFUNC(OPEN()) returns then ignore the use of the %SYSFUNC() wrapper macro function and just look at the documentation of the actual OPEN() function.

It does NOT return a boolean 0/1 answer.  Instead it returns the File handle (or in this case what the documentation calls a table-id) that is required to be used by the other functions that can operate on an open dataset.

If the OPEN() fails then it returns 0 instead of an actual number.

If the OPEN() succeeds then you need to make sure to call CLOSE(), passing the in the file handle OPEN() generated, so you close it.

[Kurt_Bremser]

Also see VARNUM Function