save(filename, var) cant find workspace variable even if it exist

So you can see that variable in your workspace, but which workspace? Every function has its own workspace, and unless these are nested functions they do not have access to variables which are inside other functions, or in the base workspace.

The workspace shown here seems to be the base workspace, which has nothing to do with the workspace of the function pushbutton_saveTest_Callback. There is no variable in its workspace called NewTest, so you get the error.

Note that there are variables listBoxItems and newTestName which do not appear in the workspace in the screen-shot: does this make you a little suspicious about which workspace this is? (although an error would remove then anyway..)

Lines 293 has newTest, line 302 has NewTest. Is this intentional?

The solution is to learn to use MATLAB's debugging tools properly. This lets you view any workspace, step through code and detect when specific events occur, and much more. Set a break point in that function (e.g. line 281), and then step through using F10 button. It will show you the function's workspace (not the base workspace), and you can see which variables actually exist there...

Although you might be tempted to access data in the base workspace from withing functions, I would advise against this. This is poor programing style, and not at all robust. Instead learn how to pass variables properly between functions and between workspaces. For example, using assignin and evalin are usually signs of bad variable handling.

Joakim Magnusson 2015-6-24

Thanks for the help, i understand how the different workspaces work now i think, i didn't know that every function had it's own workspace!

Stephen23 2015-6-24

编辑：Stephen23 2015-6-24

My pleasure!

It is levels of abstraction: suddenly thinking about multiple workspaces also means more complicated planning... but also more power! Please ask if you have any questions about how to use workspaces. Start small, look at the docs, find some examples on FEX, try out how it works... Good luck!

EDIT: one of the key things to understanding about functions is that they encapsulate and abstract some operation. It should not be required to poke around other workspaces because the whole point of a function is that it is a black box: all that matter is the input and output, not what happens in between (i.e. how it does it). This is the point of having separate workspaces... they keep operations conceptually independent.

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Answer 2

Joakim Magnusson 2015-6-24

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https://ww2.mathworks.cn/matlabcentral/answers/225073-save-filename-var-cant-find-workspace-variable-even-if-it-exist#answer_183795

编辑：Joakim Magnusson 2015-6-24

I found a solution. Instead of assigning my struct to the base workspace, i just created a variable with my struct within my function, and then just used save like this, i guess the variable i created exists in the function workspace and that save is accessing the functions workspace, correct me if i'm wrong!

structData = getNewTest(handles,newTestName);

save('NewTest.mat','structData');

(getNewTest returns the struct i want to save)

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