topic Re: Reverse a string without using REVERSE in SAS Programming

Reverse a string without using REVERSE

kindbe17 — Wed, 03 May 2023 10:20:32 GMT

hi, can you help me to reverse a string without using REVERSE function?

String 'i just want to play a Game'

Re: Reverse a string without using REVERSE

PaigeMiller — Wed, 03 May 2023 10:21:33 GMT

Why would you want to avoid using the exact function that does EXACTLY what you want?

Re: Reverse a string without using REVERSE

Oligolas — Wed, 03 May 2023 11:10:05 GMT

Hi,

you can do that for fun, I currently see 2 ways.

data test;
   length string $50;
   string='i just want to play a Game      ';
run;

*use the $reversw. format;
data want;
   set test;
   string2=put(string,$REVERS32767.);
run;

*Build your reverse string char by char starting from the end;
data want;
   set test;
   length string2 $50;
   retain string2;
   string2='';
   j=0;
   do i=lengthn(string) to 1 by -1;
      j+1;
      string2=substrn(string2,1,j)||substrn(string,i,1);
      put string2=;
   end;
run;

Re: Reverse a string without using REVERSE

drdivago — Wed, 03 May 2023 11:23:50 GMT

This program does it:

%let str = %str(i just want to play a Game);
%let len = %length(&str);

data _null_;
length str_in str_out $ &len;
str_in = "&str";
do i = 1 to &len;
substr(str_out, i, 1) = substr(str_in, &len + 1 - i, 1);
end;
put str_in= str_out=;
run;