SAS宏程序中的查询

%macro VarExist(ds,var);
    %local rc dsid result;
    %let dsid=%sysfunc(open(&ds));
    %if %sysfunc(varnum(&dsid, &var)) > 0 %then %do;
        %let result=1;
        %put NOTE: Var &var exists in &ds;
    %end;
    %else %do;
        %let result=0;
        %put NOTE: Var &var not exists in &ds;
    %end;
    %let rc=%sysfunc(close(&dsid));
    &result
%mend VarExist;

%macro DirExist(dir) ; 
   %local rc fileref return; 
   %let rc = %sysfunc(filename(fileref, &dir)) ; 
   %if %sysfunc(fexist(&fileref))  %then %let return=1;    
   %else %let return=0;
   &return
%mend DirExist;

%let fexist=1;

filename fexist pipe "ls &dir.*.txt";

data _null_;
    infile fexist truncover end=eof;
    input;
    if prxmatch('/(\*\.txt not found)/', _INFILE_) then call symputx('fexist', 0);
run;

filename fexist clear;