Pass objects into function

Question

ac_bm_mat 2022-4-28

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1707125-pass-objects-into-function

回答： Walter Roberson 2022-4-28

classdef myClass
    properties
        data
    end
    methods
        function h = myClass(data)
            h.data = data  ;
        end
    end
end

This is a class defined and I want to pass its object into a function like shown in the below:

h = myClass(0);
chg(h);
h.data
function chg(h)
h.data = h.data+2;
end

But line h.data prints 0 instead of 2. Why is that and where is the mistake in my code.

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Answer 1

Walter Roberson 2022-4-28

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1707125-pass-objects-into-function#answer_952885

You are using a value class, not a handle class. You change h.data inside the chg function, and that revised object gets returnedas a value. But you do not assign the results back over top of h; you just have semi-colon on the end of the line, so the result of the chg() function is not even displayed.

If you want to be able to call functions like that and have the properties changed without having to assign over-top of the existing object, then you need to switch to using a handle class.