Can this be improved? Rot13 Encode & Decode

Hello,

Im a new student studying computer science and we have recently started learning Matlab. (2-3 Weeks so still very novice!)

I was given a task of creating two scripts to both encode and decode the rot13 cypher. I believe I have completed them but just wanted to see if you guys can spot any

rookie mistakes or any improvements you would make? Thanks for any help!

Encode :

function [ciphermessage] = rot13_encode(plainmessage)
ciphermessage = plainmessage + 13;
for i=1:length(ciphermessage)
    if(ciphermessage(i)>90)
        ciphermessage(i) = ciphermessage(i) - 26;
    end    
end
ciphermessage = char(ciphermessage);
end

Decode:

function [ciphermessage] = rot13_encode(plainmessage)
ciphermessage = plainmessage - 13;
for i=1:length(ciphermessage)
    if(ciphermessage(i) < 65)
        ciphermessage(i) = ciphermessage(i) + 26;
    end
end
ciphermessage = char(ciphermessage);
end

Answer 1

[Sid Singh]

Hi, you should rename your decoding function, it is very misleading.

Instead of using the for loop, you can use logical indexing to make it more MATLAB like.

idx = ciphermessage>90;
ciphermessage(idx) = ciphermessage(idx) - 26;

Also your code doesn't work for lowercase ASCII. Maybe you can improve it to support this as well.