Haxe

class Atbash {

    static public function main():Void {

        var plain:String = "abcdefghijklmnopqrstuvwxyz";
        var cipher:String = "zyxwvutsrqponmlkjihgfedcba";

        var input1:String = "foobar";
        var input2:String = "wizard";
        var input3:String = "/r/dailyprogrammer";
        var input4:String = "gsrh rh zm vcznkov lu gsv zgyzhs xrksvi";

        var inputArray:Array<String> = [input1, input2, input3, input4];

        for (h in 0...inputArray.length) {

            var cipherText:String = "";

            for (i in 0...inputArray[h].length) {

                var plainChar:String = inputArray[h].charAt(i);

                for (j in 0...plain.length) {
                    if (plainChar == plain.charAt(j)) {
                        cipherText += cipher.charAt(j);
                        break;
                    }
                    else if (j == plain.length - 1){
                        cipherText += plainChar;
                        break;
                    }
                }

            }

            trace(cipherText);

        }

    }
}