MATLAB: How to tell the class of a variable (non-numeric) in a program

cell structure

I am reading a header from files. Most of the time, this header is a cell, but sometime it can be a structure with the cell being a field in the struct.

I need to identify the class of the header after I read the file so I can program accordingly.

Any suggestions?

Thanks,

Feng

Best Answer

You can use isa

>> help isa

Related Solutions

MATLAB: Access arbitrary class from MATLAB Engine interface

A trick is to convert any OOP class object to a regular structure in the MATLAB side:

ME = MException('a:b','err');
s = struct(ME);

Note that a warning is issued that any private, protected, or hidden properties of the object will become public fields in the new structure:

>> s
s = 
             type: {[0]  ''}
    hasBeenCaught: 0
       identifier: 'a:b'
          message: 'err'
            cause: {}
            stack: [0x1 struct]
     defaultstack: [0x1 struct]
        arguments: {}

Now you can retrieve the new variable using the Engine API, and handle it as a regular structure:

mxArray *s = engGetVariable(ep, "s");
mxArray *identifier = mxGetField(s, 0, "identifier");
mxArray *message = mxGetField(s, 0, "message");

MATLAB: How to create a binary to decimal/decimal to binary function file

You made several mistakes in your code, lets have a look through it. Firstly you define the function with

function output = cenversion(input)

But notice how you specify the input argument name input. This is immediately going to cause you problems, because this is also the name of the inbuilt input function, which you also want to use. You should never shadow inbuilt functions or variables like this: avoid naming any of your own variables or functions with the same names as inbuilt ones.

Then you try to check the user-selection with isa(input,'1'), but when you read the documentation for isa , this syntax is nowhere to be found. isa check for a particular class, and '1' is not a known class name, so this is never going to work.

Try this code instead:

function out = binXdec(val)  
fprintf('Available options:\t 1 = decimal to binary \t 2 = binary to decimal\n') 
switch input('Please select your option: ','s')
    case '1'
        out = dec2bin(val);
    case '2'
        out = bin2dec(val);
end
end

Note how I used the more robust syntax for input, with the second optional 's' argument, and did not shadow any inbuilt functions or variables, and used the simpler fprintf(...) rather than disp(sprintf(...)) When I save this and run it, I get this in my command window:

>> binXdec(123)
Available options:   1 = decimal to binary    2 = binary to decimal
Please select your option: 1
ans =
1111011

Best Answer

Related Solutions

MATLAB: Access arbitrary class from MATLAB Engine interface

MATLAB: How to create a binary to decimal/decimal to binary function file

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