MATLAB: Does ishghandle(0) alwys return true

Question

Why does

ishghandle(0)

return true, even if there is no existent graphic object (actually, I executed this line of code first after Matlab startup).

Answer 1

Because the graphics root always exists:

https://www.mathworks.com/help/matlab/creating_plots/graphics-objects.html

Using zero is discouraged now, but in versions prior to R2014b was equivalent to groot:

https://www.mathworks.com/help/matlab/ref/groot.html