Add Reverse String in Rexx (#4503)

Author: EmilyMenken

archive/r/rexx/reverse-string.rexx

@@ -0,0 +1,19 @@
+/* Reverse-String */
+
+parse arg inputString
+if inputString = "" then exit  /* exits right away if there is no input! */
+
+say reverseString(inputString)
+exit
+
+reverseString:
+parse arg str
+length = length(str)
+reversed = ""
+
+do i = length to 1 by -1
+reversed = reversed || substr(str, i, 1)
+end
+
+return reversed 
+/* Req: Hello, World   Expected Res: dlroW ,olleH */