"Undefined function for input arguments of type 'char'" but the function is designed to take chars.

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Isaac Friedman 2020-1-24

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/501883-undefined-function-for-input-arguments-of-type-char-but-the-function-is-designed-to-take-chars

评论： Rik 2020-1-24

I'm trying to call a function when a button is pressed in an app. I've created a class containing all the relevant functions in a static method (many of the functions reference one another, which is where these issues start to arrise). The App takes 2 files, chosen by the user, and feeds them to the function called by the button press. Here's the function call:

        function SelectButtonPushed(app, event)
            disp(app.SettingsFileEditField.Value)
            disp(app.AssemblyEditField.Value)
            BlockGenFunctions.CreateInputArrayFromFile(convertCharsToStrings(app.SettingsFileEditField.Value), convertCharsToStrings(app.AssemblyEditField.Value), [-500, 0]);
        end

The error comes when that function calls another function. Here's the complete error message:

Undefined function 'InputChunk' for input arguments of type 'char'.
Error in BlockGenFunctions.CreateInputArrayFromFile (line 115)
                InputChunk(cn, simFileName, 0 + coord(1),240*(i-1) + coord(2), i);

The issue with that is, the function is specifically designed to tach character vectors and/or strings. Here's the important parts of the function in question:

        function InputChunk(chunkName, docname, modX, modY, index)
            %create a subsystem to keep things organized
            locName = strcat(docname, '/', chunkName); %the name of the document and subsystem where the chunk is being built
            add_block('simulink/Ports & Subsystems/Subsystem',locName);
            set_param(locName,'position',[-200+modX,0+modY,200+modX,200+modY]);
            %...
            %create annotation at the top of the input chunk
            note = Simulink.Annotation(strcat(locName,'/', chunkName),'HorizontalAlignment', 'center');
            %etc
        end

So if the function specifically calls for char vectors, why is this error thrown?

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Answer 1

Rik 2020-1-24

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/501883-undefined-function-for-input-arguments-of-type-char-but-the-function-is-designed-to-take-chars#answer_411887

Generally the errors for functions that you have written yourself will not be this descriptive, unless you make them this descpritive yourself. The cause of this error tends to be that Matlab is unable to locate the function you are trying to call.

Set a breakpoint at the line of code that is calling the InputChunk function and execute

which InputChunk -all

That should give you the answer whether or not Matlab is able to find your function. If it doesn't show up, you need to make sure this function is either in the m file of the calling function, or is in an individual file on your path (and/or current directory).

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Isaac Friedman 2020-1-24

编辑：Isaac Friedman 2020-1-24

It is possible if you define those other functions outside of the classdef i.e.:

classdef BlockGenFunctions
    methods(Static)
        function CreateInputArrayFromFile ()
            %stuff goes here
            InputChunk () %function call
            %some other stuff
        end
    end
end
function InputChunk ()
    %different stuff goes here
end