A-M baby

Task/Caesar-cipher/Icon/caesar-cipher.icon

@@ -0,0 +1,16 @@
+procedure main()
+ctext := caesar(ptext := map("The quick brown fox jumped over the lazy dog"))
+dtext := caesar(ctext,,"decrypt")
+write("Plain text  = ",image(ptext))
+write("Encphered text = ",image(ctext))
+write("Decphered text = ",image(dtext))
+end
+
+procedure caesar(text,k,mode)   #: mono-alphabetic shift cipher
+/k := 3
+k := (((k % *&lcase) + *&lcase) % *&lcase) + 1
+case mode of {
+  &null|"e"|"encrypt": return map(text,&lcase,(&lcase||&lcase)[k+:*&lcase])
+  "d"|"decrypt"      : return map(text,(&lcase||&lcase)[k+:*&lcase],&lcase)
+  }
+end