# Need to utilise only letter ASCII in Caesar Cipher Code

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Bozza on 11 Sep 2022
Edited: Bozza on 7 Oct 2022
Hello,
I am currently creating a Caesar cipher code and need help, please:
1. A caesar code reverses letter order and capitalisation.
I have written a short code below, which performs the shift correctly, however, I am unsure how to reverse capitalisation, and only edit the letters.
function [out_str] = str_edit(in_str, shift)
char_set = char(32):char(126);
[out_str] = char(in_str+shift);
end

Walter Roberson on 11 Sep 2022
Hint:
T('A':'Z') = circshift('a':'z', count)
encoded = T(msg)
Bozza on 13 Sep 2022
Thanks for helping. I'm quite unfamiliar with Matlab, so I am unsure how to implement this into my code?
Walter Roberson on 13 Sep 2022
Example:
T = char(1):char(255);
T('A':'C') = 'bca';
T('a':'c') = 'BCA';
msg = 'Call a cab!'
msg = 'Call a cab!'
T(msg)
ans = 'aBll B ABC!'
What was uppercase A to C become lower-case and also shifted by 1. What was lowercase a to c become upper-case and also shifted by 1. Things outside of A B C a b c are not affected.
If you calculate the replacement vector based upon your shift count, then the indexing of T with the msg does all of the case changing and shifting at the same time, without any need of a for loop.