OR statement in MATLAB issue

Hey guys so I have this problem with code assigned to 'x' variable. I want to use OR statement (i.e. if strcmp of x is Black OR Brown OR Orange, then display 'Input saved') and move on to variable 'p'. But when I enter anything (even a given colour) or nothing at all and press enter, then the program would loop back to x. How do I fix this?

Please help

Thank you <3 :)

        x = [];
        while isempty(x)
        x = lower(input('Select colour for Disc1: "Black", "Brown", "Orange", 's'));
            if strcmp(x, 'Black') || strcmp(x,'Brown') || strcmp(x,'Orange')
            disp('Input saved')
            else
            disp('Error: Please choose a colour')
            x = [];
            end
        end

        p = [];
        while isempty(p)
        p = lower(input('Select colour for Disc2: "Black", "Brown", "Orange", 's'));
        end

[Viraj Rodrigo]

Oh yeah btw guys the variables 'x' and 'p' are from a function script that i created before, just wanted to let you know but i dont think it would make any difference :) I still need to know how to use OR statement as stated in the question.

Any help is highly appreciated

Thank you <3

Answer 1

[Ameer Hamza]

In this line

 x = lower(input('Select colour for Disc1: "Black", "Brown", "Orange", s'));

here you are using lower, whereas, in next line, you are making a comparison with "Black". This condition is failing due to case difference.

Answer 2

[John D'Errico]

While you want to understand the issue of how to use strcmp, a better test is to not do so at all!

So you might use strcmpi, which does a case insensitive test instead.

Better and simpler yet? Use ismember.

if ismember(lower(x), {'black' 'brown' 'orange'})

Do you really want to understand why your code using strcmp failed? Sigh. :)

x = 'Black'
x =
    'Black'

x = lower(x)
x =
    'black'

strcmp(x,'Black')
ans =
  logical
   0

Of course they are not the same. You converted the input to all lower case. But then you compared x to an upper case color name.

That is why strcmpi helps.

x
x =
    'black'

strcmpi(x,'Black')
ans =
  logical
   1

But still, USE ISMEMBER.