Urgent Question about comparing string to a indexed cell array number. (Assignment due tomorrow)

I trying to do a problem out my matlab book for school. Basically it asks the user to input a type of shipping which i wrote like this:

    type=input('Enter the type of shipping','s');

and later in the program im using the variable type in an if statement like this:

    C={'Ground', 'Express', 'Overnight')

    for k=1:3
       if type == C{k}
         disp(yes)
    end

when i execute this it will display "yes" for the first iteration of the loop but after the second it will give me an error saying:

    Error using  == ,Matrix dimensions must agree.

Answer 1

[Star Strider]

I would use the strcmpi function to find the index of the matching shipping method:

shipmthd = 'overnight';
C={'Ground', 'Express', 'Overnight'};
k = find(strcmpi(shipmthd, C));

[Matthew]

Hey thanks for your answer. Upon further research i discovered that you cant compare words of different lengths using '==', it will return an error hence why when it would compare Ground with Express an error would display. I ended up using something similar to your answer. Thanks again.

[Star Strider]

My pleasure!

Answer 2

[Image Analyst]

Hint: Try the ismember() function.

[Matthew]

Thanks for the quick answer, but my real questions is, why does my method work for the first iteration of k but none after.

[Matthew]

Also i forgot to include that i was inputting Ground for type when i was trying this.

[Image Analyst]

"type" is a built in command and should not be used for a variable name.

What did you type in? When you incorrectly use == to compare strings, it compares all the elements and all must match. If one does not match, the "if" is not true. Try this with various values for s and observe what happens:

t='abc'
s = 'axa'
t == s
if t == s
  fprintf('Match\n');
else
  fprintf('No match\n');
end

The proper way is to use string comparison functions like ismember, strcmpi(), strcmp(), etc.

[Image Analyst]

theType = 'Ground';
C={'Ground', 'Express', 'Overnight'};
[~, index] = ismember(theType, C)

You can also use menu instead of input():

C={'Ground', 'Express', 'Overnight'};
button = menu('Shipping Method', C)