Define multible Global Variables

Hello,

i used to declare global variables like this.

global p
% Körper 1 
    p.b1     = 1;
    p.h1     = 0.6;
    p.h1s    = 0.3;
    p.hp    = 0.5;
...

This isn´t working anymore. does somebody know why?

Answer 1

[Adam Danz]

Maybe it's a sign from the god of "Best Practice" to not use global variables ;)

Your declarations should (still) work. Don't forget that you must declare the global variables again in the local workspace in order to access them.

global p
p.b1 = 1; 
p.h1 = 0.6; 

function dontUseGlobalVariables()
   global p
   % Now you have access to the p structure. 
end

Or maybe a clear() command cleared your global variable between it's declaration and its retreival.

But again, please see this link to this comment to learn why global variables are a sign of bad programming.

https://www.mathworks.com/matlabcentral/answers/267826-on-global-variables#comment_342224

[John D'Errico]

Good function name. :)

[Rik]

The only additional advice I would give is this: if you absolutely need to use globals, use a long name that contains the name of your top level function and is very descriptive. Using a long avoids collisions with other functions that might be using a similarly named variable. You have 63 characters for your variable name, you should use more than just 1.

I you think the name is too long and cumbersome to work with, create a temporary copy internal to your function. If you are not modifying the global there is no downside, thanks to the copy-on-write behavior of Matlab.