How to use SAS macro in a SAS Dataset -

i want use macro call in data step. below macro , invocation in data step isnt working. can guys please suggest way make work.

 %macro xscan(string, delimiter, word_number);   %let len1=%length(&string); /*computing length of string*/  %let len=%eval(&len1+1);  %let sub=%scan(&string,&word_number,"&delimiter");    %if &word_number ge 0 %then %do;  %let pos=%index(&string,&sub); /* locate position while reading left right*/  %end;   %if &word_number lt 0 %then %do;  data _null_;  pos=find("&string","&sub",-&len);  call symput("pos",pos);  run;  %end;   %let strg=%substr(&string,&pos); /* extract substring*/   %put string &strg;  %mend;   data work.in_data; length in_string $50; in_string = “a bb ccc dddd bb eeeee”;  output; in_string = “aa b cc aa dee”;  output;  run;   data work.out_data; set work.in_data; length sub_str $50; start_word_num = -(_n_ +1); sub_str = %xscan(in_string,’ ‘, start_word_num);  run;   proc print; run; 

if macro used inside datastep, write more using datastep functions instead of making complicated macro functions. there plenty of sas string functions allow accomplish appears want in far less code.