How to make Matlab give different answers for different text inputs of different lengths

A = input('Ask me anything: ','s');
if A==('Are you sentient?')
    disp('Yes')
else
    disp('Ask me anything but that')
end

This only works if I ask "Are you sentient?", or input a sentence of equal length. So if I input "abc def ghijklmno" It'll take it and give the else answer, but if I simply ask it "Yes?" it gives me the error, "Arrays have incompatible sizes for this operation" What am I doing wrong?

Answer 1

[Stephen23]

"What am I doing wrong?"

You are using EQ (i.e. ==) for character arrays, which performs a character-by-character comparison (exactly like using EQ on numeric arrays). If you want to compare the entire text use STRCMP, STRCMPI, or similar:

if strcmpi(A,'Are you sentient?')

https://www.mathworks.com/help/matlab/matlab_prog/string-comparisons.html#CompareSortAndCharacterizeTextExample-4

[Stephen23]

Note how EQ works for character arrays:

'cat' == 'hat'

ans = 1×3 logical array
   0   1   1

which is just like EQ for numeric arrays:

[1,2,3] == [0,2,3]

ans = 1×3 logical array
   0   1   1

This operation only works if the array sizes are compatible:

https://www.mathworks.com/help/matlab/matlab_prog/compatible-array-sizes-for-basic-operations.html

(which yours are not, as you noted yourself)

[Noah Cross]

Nice, that makes sense. Thanks for the answer.

Answer 2

[DGM]

I figured that for multiple cases, it would be neater to use a switch-case.

A = input('How do you eat your oatmeal?: ','s');

switch lower(A)
    case 'hot'
        disp('Wow! Me too! We have so much in common.')
    case 'cold'
        disp('That''s kind of gross.')
    case {'with my mouth','with a spoon'} % you can use grouped cases
        disp('Ha ha, mister funny man.')
    otherwise
        disp('I didn''t expect you to say that')
end

[Noah Cross]

See that's what I was actually trying to remember. Thank you.

Answer 3

[Chunru]

A = input('Ask me anything: ','s');
if strcmpi(A, 'Yes')   % compare string (case insensitive)
    disp('Yes')
else
    disp('Ask me anything but that')
end

[Noah Cross]

Works perfectly. Thanks