using switch, case and comparing strings

Question

Keith Holmlund 2018-6-21

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https://ww2.mathworks.cn/matlabcentral/answers/406869-using-switch-case-and-comparing-strings

评论： belhassan haj mansour 2019-1-9

I am using a function with varargin that imports strings and numbers but the first input is always a string. based off what it says, using switch and case, I want the function to do something different. So if for example, str = char(varargin{1}) = 'hot dog' and I had

switch str

case str == 'hot dog'

case str == 'burger'

When I do this I get an error, what am I doing wrong

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dpb 2018-6-21

编辑：dpb 2018-6-21

在 MATLAB Online 中打开

str = varargin{1} = 'hot dog'

is illegal syntax and the SWITCH construct is missing any action statements in the cases plus isn't closed.

A properly formed SWITCH construct will work just fine with string or character variables; it will have an issue with a cellstr() argument unless you take care to dereference it.

We need to see the actual function to debug, not just bits and pieces.

Keith Holmlund 2018-6-21

编辑：Keith Holmlund 2018-6-21

在 MATLAB Online 中打开

It looks something like this, The first input is 'hot dog'. When run I enter Menu('hot dog','ketchup'). I am getting an error at the first case line

 function Menu(varargin)
 cat = char(varargin{1});
 switch cat
       case cat == 'hot dog'
            condiment = char(varargin{2});
            subfunction
       case cat == 'burger'
            bun = char(varargin{2});
            subfunction2
 end

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Answer 1

OCDER 2018-6-21

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https://ww2.mathworks.cn/matlabcentral/answers/406869-using-switch-case-and-comparing-strings#answer_325737

编辑：OCDER 2018-6-21

在 MATLAB Online 中打开

The switch statement is used incorrectly. Remove the "str ==" after case.

function Menu(varargin)
%varargin = {'hot dog', 1, 2, 3};
str = varargin{1};
switch lower(str) %make it case insensitive. all lower cases
    case 'hot dog'
        disp('Delicious hot dogs!')
    case 'burger'
        disp('Mouth-watering burgers!')
end

Actually, what was the Error message? I should have waited for your response to @dpb since there are multiple issues, as already pointed out.

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OCDER 2018-6-21

编辑：OCDER 2018-6-21

在 MATLAB Online 中打开

Remove 'cat == ' after your case. And DO NOT use "cat" as a variable, as that's a built-in matlab function for concatenate arrays.

help cat

I like to label my variables with 1st letter caps, just in case I accidentally name a variable the same as a matlab function.

Walter Roberson 2018-6-21

I tested with OCDER's code, and it looks fine to me.

OCDER's code does not use any string data types and so could not get that message.

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Answer 2

belhassan haj mansour 2019-1-9

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/406869-using-switch-case-and-comparing-strings#answer_355723

编辑：belhassan haj mansour 2019-1-9

HELLO

im trying to control a rocker switch with another one in app designer, for example i have rockerswitch1 in the position 'off' and rockerswitch2 also in position 'off' . what i need is when i put rockerswitch1 in position 'on', the rockerswitch 2 become in the position 'on' too but i can't find the right function to do so

CAN ANYONE HELP ME WITH THIS PLEASE ?