How to modify narginchk in DES matlab code

I have downloaded DES code from file exchange and try to modify it a bit but it gives error which I cannot figure out whats wrong with hit. Here is the part of the code

function [varargout] = DES(~,~)
%DES: Data Encryption Standard
% Encrypt/Decrypt a 64-bit message using a 64-bit key using the Feistel Network
% -------------------------------------------------------------------------
% Inputs: 
        input64 = '1234567890123456789012345678901234567890123456789012345678901234' ;
        mode = 'ENC';
        key ='aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa';
        Outputs:
%   varargout{1} = output64, a 64-bit message after encryption/decryption
%   varargout{2} = a 64-bit key, if a 64-bit key is not provided as an input
% -------------------------------------------------------------------------
% Demos:
                           0. Initialization                           %%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% 0.1 check input
%error(nargchk(1,3,nargin));
narginchk(1,3);
switch nargin
    case 1
    

narginchk(1,3); error at this line.

>> DES

Error using DES (line 64)

Not enough input arguments.

    ....

Answer 1

[Walter Roberson]

You should not modify it to assign input64 and mode and key in the code. You should define the function as accepting up to 3 input variables, input64, mode and key and you should pass the desired values into the function.

If you insist on defining the variables inside the function, then comment out the narginchk line and the entire switch block with all cases.

[sadiqa ilyas]

When I run the code downloaded from file exchange gives the same error that is

error(nargchk(1,3,nargin));

Can u plz figure out what is wrong

[Walter Roberson]

If you are using the FEX contribution DES then you have to pass arguments to it when you run it.

k = keygen;
msg = 'To be, or not to be!'
emsg = DES(msg, k, 'ENC');
dmsg = DES(emsg, k, 'DEC')

[sadiqa ilyas]

Thanks