How am I gonna do if I just want this to show me only Decoy message: Invalid rescue day . And the changes will not affect other codes?

clc;clear
C1 = input('Please enter a code to break: ' , 's');
if length(C1) ~= 6
    disp('Decoy message: Not a six-digit number.');
else
    A = mod(sum(C1 - '0'),2);
if A == 1
    disp('Decoy message: Sum is odd.')
else
    C2 = (C1(1) - '0') * (C1(2) - '0') - (C1(3) - '0');
switch C2
    case 1  
        Day = 'Rescue on Monday';
    case 2
        Day = 'Rescue on Tuesday';
    case 3
        Day = 'Rescue on Wednesday';
    case 4 
        Day = 'Rescue on Thursday';
    case 5
        Day = 'Rescue on Friday';
    case 6 
        Day = 'Rescue on Saturday';
    case 7
        Day = 'Rescue on Sunday';
    otherwise
        disp('Decoy message: Invalid rescue day.');
end
F1 = str2double(C1(4));
F2 = str2double(C1(5));
F3 = str2double(C1(6));
if mod(F1,3) == 0
    B = F2 - F3;
else
    B = F3 - F2;
end
switch(B)
    case 1
        Position = ' at the bridge.';
    case 2
        Position = ' at the library.';
    case 3
        Position = ' at the river crossing.';
    case 4
        Position = ' at the airport.';
    case 5
        Position = ' at the bus terminal.';
    case 6
        Position = ' at the hospital.';
    case 7
        Position = ' at St. Petes Church.';
    otherwise
        disp('Decoy message: Invalid rendezvous point.');
end
disp([Day , Position])
end
end

When I enter 397090, I will get both:

Decoy message: Invalid rescue day.

Decoy message: Invalid rendezvous point.

and some other error messages:

Unrecognized function or variable 'Day'.

Error in Untitled5 (line 69)

disp([Day , Position])

How am I gonna do if I just want this to show me only Decoy message: Invalid rescue day . And the changes will not affect other codes?

Answer 1

[Walter Roberson]

Before

switch C2

insert

failed = false;

After

        disp('Decoy message: Invalid rescue day.');

insert

        failed = true;

Put the

switch(B)

inside

if ~failed

[Minhao Wang]

For the last two steps,is it like

if ~failed
    switch(B)
end

[Walter Roberson]

Yes, together with all the appropriate case statements that belong to switch(B); they all go before the "end"

[Minhao Wang]

Thank you. And I got another question

if I enter :918990

it will give me decoy message: Invalid rendezvous point.

But also there is a error massage showed up:

Unrecognized function or variable 'Position'.

Error in Untitled5 (line 72)

disp([Day , Position])

Can I avoid this?

[Walter Roberson]

Make sure the disp() is inside your "if ~failed"

[Minhao Wang]

Sorry, like where?

clc;clear
C1 = input('Please enter a code to break: ' , 's');
if length(C1) ~= 6
    disp('Decoy message: Not a six-digit number.');
else
    A = mod(sum(C1 - '0'),2);
if A == 1
    disp('Decoy message: Sum is odd.')
else
    C2 = (C1(1) - '0') * (C1(2) - '0') - (C1(3) - '0');
    failed = false;
switch C2
    case 1  
        Day = 'Rescue on Monday';
    case 2
        Day = 'Rescue on Tuesday';
    case 3
        Day = 'Rescue on Wednesday';
    case 4 
        Day = 'Rescue on Thursday';
    case 5
        Day = 'Rescue on Friday';
    case 6 
        Day = 'Rescue on Saturday';
    case 7
        Day = 'Rescue on Sunday';
    otherwise
        disp('Decoy message: Invalid rescue day.');
        failed = true;
end
F1 = str2double(C1(4));
F2 = str2double(C1(5));
F3 = str2double(C1(6));
if mod(F1,3) == 0
    B = F2 - F3;
else
    B = F3 - F2;
end
if ~failed 
    switch(B)
    case 1
        Position = ' at the bridge.';
    case 2
        Position = ' at the library.';
    case 3
        Position = ' at the river crossing.';
    case 4
        Position = ' at the airport.';
    case 5
        Position = ' at the bus terminal.';
    case 6
        Position = ' at the hospital.';
    case 7
        Position = ' at St. Petes Church.';
    otherwise
        disp('Decoy message: Invalid rendezvous point.');
    end
disp([Day , Position])
end
end
end

[Minhao Wang]

I don't quite get it, if you put disp([Day , Position]) in switch(B),

right below disp('Decoy message: Invalid rendezvous point.'); This will affect the original code...

[Walter Roberson]

Well, instead you could change the

        disp('Decoy message: Invalid rescue day.');

to

        Day = 'Decoy message: Invalid rescue day.';

and change

        disp('Decoy message: Invalid rendezvous point.');

to

        Position = 'Decoy message: Invalid rendezvous point.';

[Minhao Wang]

I tired

otherwise
        disp('Decoy message: Invalid rendezvous point.');
        disp([Day , Position])
        end

or

otherwise
        Position: 'Decoy message: Invalid rendezvous point.';
        disp([Day , Position])
        end

or with the

disp([Day , Position]) after end

It just does not work, what I want is if I enter 918990, I only want it shows me

Decoy message: Invalid rendezvous point.

with no error messages showed up.

[Minhao Wang]

problem solved! thank you!