Can handle class be used to simulate "Pointer" in C language?

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Shunchao Wu 2011-11-15

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If I define a "Ptr" class as following:

classdef Ptr < handle
    properties
        data
    end
end

then, objects of Ptr will behave like pointers in C language.

Is this true, guys?

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Shunchao Wu 2011-11-15

Why is the "Bytes" 0 in Variable Editor?

The "Bytes" of a field of a struct, or a property of a object, is 0.

Verified on 2008a and 1010b.

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回答（2 个）

Daniel Shub 2011-11-15

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Objects of the handle class are not identical to pointers. When you pass an object to a function (whether it is a value class or a handle class), MATLAB does not immediately make a copy of the object. It is almost like it passes a pointer (but it is not a pointer). MATLAB has a complicated COW and tries not to copy the object unless it needs to. With a high level language of MATLAB you have to give up some of the control on memory management and hope MATLAB behaves in a reasonable manner.

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per isakson 2011-11-15

Undocumented Matlab at, http://undocumentedmatlab.com/ , might interest you.

Shunchao Wu 2011-11-16

Great website!

Thanks, isakson.

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Titus Edelhofer 2011-11-15

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在 MATLAB Online 中打开

Hi,

"then objects of Ptr will behave like pointers". If the behaviour you mean is that once you change a Ptr, all other variables that "point" to the same object are changed as well, then yes. Example:

x = Ptr;
y = x;  % both x and y "point" to the same object
x.data = 2; % now y.data is 2 as well

But I would say that "reference" like the & in C++ comes nearer to what handle classes are ...

Titus

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Titus Edelhofer 2011-11-16

hmm, why not? When you pass an object by reference to a function, the function may change the underlying/referenced object. Of course only, as long as you don't pass a const reference ... Or do I remember entirely wrong, since my C++ programming is about 10 years ago by now ;-).

Shunchao Wu 2011-11-19