The following code requires that the filenames has the form: class1.txt class2.txt ... class100.txt, and the variables are in the order: Name ID Gender Edate Bdate.
If there is no variable names in the text file, the firstobs=1 should be used.

%macro merge(num);
  proc printto log=_null_;
  %do i=1 %to #
    proc import out=class&i datafile="c:\docs\class&i.txt" dbms=dlm replace;
    %if i=1 %then %do;
           data class_all;
            set class&i(obs=0);
           run;
        %end;
        proc append base=class_all data=class&i;
        proc datasets lib=work nolist;
    delete class&i;
        run;
  %end;
  proc printto;
  run;
%mend;

%merge(100)

这句是干什么？还有obs=0起什么作用？

不同表内的数据需要flag吗？

假设文件都在TEMP文件夹下