Function in Separate File

Hi all. I need to convert this encryption program into 2 separate functions, one for encryption, and one for decryption. I am confused at the moment. The code below is the current code with everything in one file. How would I create 2 separate functions for the encryption and decryption? Thanks

clear
clc

%Prompts for user input
message = input('Enter a message to encode: ', 's');
encryption = message;

%Sets the terms and conditions for encoding characters, and if else then
%mapping them to themselves
for i = 1:length(encryption)
x = encryption(i);
    if x >= 'A' && x <= 'Z'
        if x >= 'U'
             x = x - 20;
        else
            x = x + 6;
        end

    elseif x>= 'a' && x <= 'z'
        if x >= 'u'
            x = x - 20;
        else
            x = x + 6;
end

end
encryption(i) = x;
end

%Same thing as above except dealing with the decryption, mapping to
%themselves if necessary.
decryption = encryption;
for i = 1:length(decryption)
x = decryption(i);
    if x >= 'A' && x <= 'Z'
        if x <= 'F'
            x = x + 20;
        else
            x = x - 6;
        end

    elseif x>= 'a' && x <= 'z'
        if x <= 'f'
            x = x + 20;
        else
            x = x - 6;
end

end
decryption(i) = x;
end

%Prints the output 
fprintf("\nMessage: %s\n\n", message);
fprintf("Encrypted: %s\n\n", encryption);
fprintf("Decrypted: %s\n\n", decryption);

Answer 1

[KALYAN ACHARJYA]

Main Script:

clear;
clc; close all;
%% Message Input
message=input('Enter a message to encode: ', 's');
encryption_message=message;
%To call encryption function
en=encryption_fun(encryption_message);
%% To call decryption function
dn=decryption_fun(en);
%% Prints the output 
fprintf('\nMessage: %s\n\n',message);
fprintf('Encrypted: %s\n\n',en);
fprintf('Decrypted: %s\n\n',dn);

Save the encryption function in differnt file (Must be in current directory, save file name as encryption_fun.m)

function encryption=encryption_fun(encryption)
%Sets the terms and conditions for encoding characters, and if else then
%mapping them to themselves
for i=1:length(encryption)
x=encryption(i);
    if x >= 'A' && x <= 'Z'
        if x >= 'U'
             x = x - 20;
        else
            x = x + 6;
        end
    elseif x>= 'a' && x <= 'z'
        if x >= 'u'
            x = x - 20;
        else
            x = x + 6;
end
end
encryption(i) = x;
end
end

Save the decryption function in differnt file (Must be in current directory, save file name as decryption_fun.m)

function decryption=decryption_fun(encryption)
decryption=encryption;
for i=1:length(decryption)
x = decryption(i);
    if x >= 'A' && x <= 'Z'
        if x <= 'F'
            x = x + 20;
        else
            x = x - 6;
        end
    elseif x>= 'a' && x <= 'z'
        if x <= 'f'
            x = x + 20;
        else
            x = x - 6;
end
end
decryption(i) = x;
end
end

Now run the main code (First one) and results:

Enter a message to encode: Kalyan
Message: Kalyan
Encrypted: Qgregt
Decrypted: Kalyan