Caesar Cipher

[Mario]

On Sunday, 11 February 2018 at 18:28:08 UTC, Cym13 wrote:
> On Sunday, 11 February 2018 at 18:01:20 UTC, Mario wrote:
>> Hello there! I know deep Java, JavaScript, PHP, etc. but as 
>> you all probably know, that's high-level and most of them only 
>> use the heap memory.
>>
>> So I'm new to the wonderful world of low-level and the 
>> stack-heap. I started a week ago learning D (which by the 
>> moment is being easy for me) but I'm facing a big problem: I 
>> don't know how to do the exercise of 
>> https://tour.dlang.org/tour/en/basics/arrays . I really have 
>> been looking on forums and Google but I found this in Java 
>> https://stackoverflow.com/questions/10023818/shift-character-in-alphabet which is actually not the best due to Java uses other ways.
>>
>> My code is something like this:
>>
>> char[] encrypt(char[] input, char shift)
>> {
>>     auto result = input.dup;
>>     result[] += shift;
>>     return result;
>> }
>>
>>
>> What's wrong? I mean, I know that z is being converted into a 
>> symbol, but how should I fix this?
>> Thanks on forward.
>
> Your mistake has little to do with D, and more with Ceasar 
> (which is unfortunate IMHO): this cipher is usually defined 
> only on the 26 letters of the alphabet and seeing the result of 
> the assert at the end of the code it's the case here. So while 
> you're working on a full byte (256 values) you should restrict 
> yourself to the 26 lowercase ascii alpha characters.
>
> Give it a try :)

Got it, I'll give it a try with an if. Will post later the result 
so more people can get a solution with the most basic stuff.