update

Task/Caesar-cipher/D/caesar-cipher-1.d

@@ -1,20 +1,21 @@
 import std.stdio, std.traits;
 
-pure S rot(S)(in S s, in int key) if (isSomeString!S) {
-    auto res = s.dup;
+pure S rot(S)(in S s, in int key) pure /*nothrow*/
+if (isSomeString!S) {
+    auto res = s.dup; // Not nothrow.
 
-    foreach (i, ref c; res) {
+    foreach (immutable i, ref c; res) {
         if ('a' <= c && c <= 'z')
             c = ((c - 'a' + key) % 26 + 'a');
         else if ('A' <= c && c <= 'Z')
             c = ((c - 'A' + key) % 26 + 'A');
     }
-    return cast(S) res;
+    return res;
 }
 
 void main() {
-    int key = 3;
-    auto txt = "The five boxing wizards jump quickly";
+    enum key = 3;
+    immutable txt = "The five boxing wizards jump quickly";
     writeln("Original:  ", txt);
     writeln("Encrypted: ", txt.rot(key));
     writeln("Decrypted: ", txt.rot(key).rot(26 - key));

Task/Caesar-cipher/D/caesar-cipher-3.d

@@ -0,0 +1,17 @@
+import std.stdio, std.ascii, std.string, std.algorithm;
+
+string rot(in string s, in int key) pure /*nothrow*/ {
+    auto uppr = uppercase.dup.representation;
+    bringToFront(uppr[0 .. key], uppr[key .. $]);
+    auto lowr = lowercase.dup.representation;
+    bringToFront(lowr[0 .. key], lowr[key .. $]);
+    return s.translate(makeTrans(letters, cast(char[])(uppr ~ lowr)));
+}
+
+void main() {
+    enum key = 3;
+    immutable txt = "The five boxing wizards jump quickly";
+    writeln("Original:  ", txt);
+    writeln("Encrypted: ", txt.rot(key));
+    writeln("Decrypted: ", txt.rot(key).rot(26 - key));
+}

Task/Caesar-cipher/Objeck/caesar-cipher.objeck

@@ -0,0 +1,29 @@
+class Caesar {
+  function : native : Encode(enc : String, offset : Int) ~ String {
+    offset := offset % 26 + 26;
+    encoded := "";
+    enc := enc->ToLower();
+    each(i : enc) {
+      c := enc->Get(i);
+      if(c->IsChar()) {
+        j := (c - 'a' + offset) % 26;
+        encoded->Append(j + 'a');
+      }
+      else {
+        encoded->Append(c);
+      };
+    };
+
+    return encoded;
+  }
+
+  function : Decode(enc : String, offset : Int) ~ String {
+    return Encode(enc, offset * -1);
+  }
+
+  function : Main(args : String[]) ~ Nil {
+    enc := Encode("The quick brown fox Jumped over the lazy Dog", 12);
+    enc->PrintLine();
+    Decode(enc, 12)->PrintLine();
+  }
+}

Task/Caesar-cipher/Racket/caesar-cipher.rkt

@@ -0,0 +1,19 @@
+#lang racket
+
+(define A (char->integer #\A))
+(define Z (char->integer #\Z))
+(define a (char->integer #\a))
+(define z (char->integer #\z))
+
+(define (rotate c n)
+  (define cnum (char->integer c))
+  (define (shift base) (integer->char (+ base (modulo (+ n (- cnum base)) 26))))
+  (cond [(<= A cnum Z) (shift A)]
+        [(<= a cnum z) (shift a)]
+        [else c]))
+
+(define (caesar s n)
+  (list->string (for/list ([c (in-string s)]) (rotate c n))))
+
+(define (encrypt s) (caesar s 1))
+(define (decrypt s) (caesar s -1))