写漏了一个判别~
data ex;
length x $100;
infile "E:\test.txt" ;
input;
x=_infile_;
run;

data _null_;
set ex;
if _n_=1 then do;
retain id;
id=prxparse("s/[A-Za-z]{1}[a-zA-Z0-9]+\b(?= )/{$0}/");
end;
call prxchange(id,-1,x);
file "E:\test1.txt";
put x $100.;
run;

嗯！不错！高手！

data ex;
length x $100;
infile "E:\test.txt" ;
input;
x=_infile_;
run;

data _null_;
set ex;
if _n_=1 then do;
retain id;
id=prxparse("s/[A-Za-z]{1}[a-zA-Z0-9]+\b/{$0}/");
end;
call prxchange(id,-1,x);
file "E:\test1.txt";
put x $100.;
run;

学习学习。佩服啊