langs a-z

Task/Caesar-cipher/OCaml/caesar-cipher-1.ocaml

@@ -0,0 +1,51 @@
+let islower c =
+  c >= 'a' && c <= 'z'
+
+let isupper c =
+  c >= 'A' && c <= 'Z'
+
+let rot x str =
+  let upchars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+  and lowchars = "abcdefghijklmnopqrstuvwxyz" in
+  let rec decal x =
+    if x < 0 then decal (x + 26) else x
+  in
+  let x = (decal x) mod 26 in
+  let decal_up = x - (int_of_char 'A')
+  and decal_low = x - (int_of_char 'a') in
+  let len = String.length str in
+  let res = String.create len in
+  for i = 0 to pred len do
+    let c = str.[i] in
+    if islower c then
+      let j = ((int_of_char c) + decal_low) mod 26 in
+      res.[i] <- lowchars.[j]
+    else if isupper c then
+      let j = ((int_of_char c) + decal_up) mod 26 in
+      res.[i] <- upchars.[j]
+    else
+      res.[i] <- c
+  done;
+  (res)
+
+(* or in OCaml 4.00+:
+let rot x =
+  let upchars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+  and lowchars = "abcdefghijklmnopqrstuvwxyz" in
+  let rec decal x =
+    if x < 0 then decal (x + 26) else x
+  in
+  let x = (decal x) mod 26 in
+  let decal_up = x - (int_of_char 'A')
+  and decal_low = x - (int_of_char 'a') in
+  String.map (fun c ->
+    if islower c then
+      let j = ((int_of_char c) + decal_low) mod 26 in
+      lowchars.[j]
+    else if isupper c then
+      let j = ((int_of_char c) + decal_up) mod 26 in
+      upchars.[j]
+    else
+      c
+  )
+*)

Task/Caesar-cipher/OCaml/caesar-cipher-2.ocaml

@@ -0,0 +1,9 @@
+let () =
+  let key = 3 in
+  let orig = "The five boxing wizards jump quickly" in
+  let enciphered = rot key orig in
+  print_endline enciphered;
+  let deciphered = rot (- key) enciphered in
+  print_endline deciphered;
+  Printf.printf "equal: %b\n" (orig = deciphered)
+;;