Create a global variable in a GUI

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Edward 2013-9-28

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https://ww2.mathworks.cn/matlabcentral/answers/88518-create-a-global-variable-in-a-gui

评论： Miguel Reyes 2018-8-24

采纳的回答： Azzi Abdelmalek

在 MATLAB Online 中打开

Im making a gui which has a two buttons:

function button_browse_Callback(hObject, eventdata, handles)
filename = uigetfile
function button_load_Callback(hObject, eventdata, handles)
fid=fopen(filename,'rt');
....etc

but I cant do the above because button_load_Callback does not have access to filename.

how can I pass the filename from button_browse_callback to button_load_callback?

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Azzi Abdelmalek 2013-9-28

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https://ww2.mathworks.cn/matlabcentral/answers/88518-create-a-global-variable-in-a-gui#answer_98078

编辑：Azzi Abdelmalek 2013-9-28

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You don't need global variables, use guidata

function button_browse_Callback(hObject, eventdata, handles)
filename = uigetfile
...
handles.filename=filename
guidata(hObject,handles)

%-------------------------------------------------------------------------------------------------------

function button_load_Callback(hObject, eventdata, handles)
filename=handles.filename
fid=fopen(filename,'rt');
...

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Khine zar 2018-3-17

thank you !.... Your answer is helpful for me !

Miguel Reyes 2018-8-24

Thanks! for your practical idea

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Image Analyst 2013-9-28

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https://ww2.mathworks.cn/matlabcentral/answers/88518-create-a-global-variable-in-a-gui#answer_98080

编辑：Image Analyst 2015-6-26

在 MATLAB Online 中打开

Another way is to declare the variables global in every function that needs to access them.

function button_browse_Callback(hObject, eventdata, handles)
global baseFileName folder;
[baseFileName, folder] = uigetfile();
function button_load_Callback(hObject, eventdata, handles)
global baseFileName folder;
fullFileName = fullfile(folder, baseFileName);
fid=fopen(fullFileName ,'rt');

Any function that declares the variables baseFileName and folder as global will be able to see the variables. They can be created and changed in any function that has that global declaration line. Functions that do not have the global declaration line will not be able to see those variables.

Or see the FAQ: http://matlab.wikia.com/wiki/FAQ#How_can_I_share_data_between_callback_functions_in_my_GUI.28s.29.3F, and http://matlab.wikia.com/wiki/FAQ#Are_global_variables_bad.3F

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Stephen23 2015-9-21

编辑：Stephen23 2015-9-21

@John: you don't need to use globals, there are other neater and more robust tools available, as the first answer showed already: Use guidata instead.

John 2015-9-21

Hi Stephen, i know used guidata for passing values between several GUIs but now i want to execute a complex function wihtin a GUI and this function doesnt have input parameters but works with globally defined variables. Thats why i would like to do it this easy way...i thought declaring variables as global in the opening function of the mainGUI would make them visible all over the main GUIs callbacks and also for the children of the parent mainGUI... I am wrong with that right? so i always have to declare them again vefore i have access....

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