MATLAB Answers

Julian S
0

Define multible Global Variables

Asked by Julian S
on 19 May 2019
Latest activity Edited by Adam Danz
on 20 May 2019
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?

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1 Answer

Answer by Adam Danz
on 19 May 2019
Edited by Adam Danz
on 20 May 2019

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.

  2 Comments

Good function name. :)
Rik
on 19 May 2019
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.

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