Caesar cipher: Difference between revisions

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Inline

@@ Line 1,891: / Line 1,891: @@
 "The quick brown fox jumps over the lazy dog"</pre>
-====Variant====
+====Alternate version====
 . Note
-<pre>if rot(text shift) = cyphertext then rot(cyphertext -shift) = text</pre>
+<pre>if caesar(txt offset) = cyphertext then caesar(cyphertext -offset) = txt</pre>
-See « caesar-decipher » function above.
 . Program
-<lang lisp>(defconstant +rot+ "AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz")
+<lang lisp>(defconstant +a+ "AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz")
-(defun rot (text shift)
+(defun caesar (txt offset)
   (map 'string
     #'(lambda (x)
-        (if (find x +rot+)
+        (if (find x +a+)
-          (char +rot+ (mod (+ (position x +rot+) (* 2 shift)) 52))
+          (char +a+ (mod (+ (position x +a+) (* 2 offset)) 52))
           x))
-    text))</lang>
+    txt))</lang>
 . Execution
+See 1.
 {{out}}
-<pre>(rot "Ave Caesar morituri te salutant" 13)
+<pre>(caesar "Ave Caesar morituri te salutant" 13)
 Nir Pnrfne zbevghev gr fnyhgnag
-(rot "Nir Pnrfne zbevghev gr fnyhgnag" -13)
+(caesar "Nir Pnrfne zbevghev gr fnyhgnag" -13)
 Ave Caesar morituri te salutant</pre>