Theemptymethod enables you to initialize arrays of a specific class:

C = char.empty(0,7) C = Empty matrix: 0-by-7 disp(class(C)) char

Initializing an array with empty brackets ([]) produces an empty array of classdouble:

a = [];

disp(class(a)) double

You can initialize an empty array of a user-defined class. For example, the empty static method is a hidden method of theRGBColorclass defined here.

classdefColorInRGBpropertiesColor(1,3)= [1,0,0];endmethodsfunctionobj = ColorInRGB(c)ifnargin > 0 obj.Color = c;endendendend

To create an empty 0-by-5 array of classColorInRGB, call the empty method:

A = ColorInRGB.empty(0,5);

You can use theisempty,size, andlengthfunctions to identify empty object arrays. For example, create an empty array of theColorInRGBclass defined in the previous section.

A = ColorInRGB.empty(0,5); isempty(A)

ans = logical 1

size(A)

ans = 0 5

length(A)

ans = 0

Empty arrays follow array concatenation behavior. For example, create an empty array of theColorInRGBclass defined in the previous section and for a new array by concatenating instances into another array.

A = ColorInRGB.empty(0,5); B = [A A]

B = 0×10 ColorInRGB array with properties: Color

You cannot index into an empty array.

B(0,3)

Index in position 1 is invalid. Array indices must be positive integers or logical values.