Pushback button execution in a while loop

I am making a continuous measurement using while loop. But I am not saving all the measurements. I have push back button, which adds the measurement to a variable, when the user clicks on it. It should not add the measurement in the next loop to the variable. This is my intention.

How its actually working right now:

The button becomes active after first click, and adds all the measurement to the variable continuously until the end of loop..

load.x is the measurement.

function add_measure_ButtonDownFcn(hObject, eventdata, handles)
% hObject    handle to add_measure (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
handles.add_meas=1;
guidata(hObject, handles);



while i<100
    hObject = h.figureViz;
    handles = guidata(hObject);
    
    if handles.add_meas==1
         handles.add_meas=0;
         X_coord_new = [X_coord_new, load.x]
    end
end 

Answer 1

[Geoff Hayes]

Ram - in the body of your add_measure_ButtonDownFcn you do

handles.add_meas=1;
guidata(hObject, handles);

where you initialize add_meas to one and then update the handles structure. The while loop code is

while i<100
    hObject = h.figureViz;
    handles = guidata(hObject);
    
    if handles.add_meas==1
         handles.add_meas=0;
         X_coord_new = [X_coord_new, load.x]
    end
end 

where you get the latest version of the handles structure and check to see if add_meas is one. Since it is (because you have set this previously) you enter the body of the if and set add_meas field to zero...but you don't save the updated handles structure. So on the next iteration of the loop, you get the latest/saved handles structure which still has add_meas set to 1. You need to save the updated structure as

    if handles.add_meas==1
         handles.add_meas=0;
         guidata(hObject, handles);
         X_coord_new = [X_coord_new, load.x]
    end

so that you don't update the X_coord_new on the next iteration of the loop.

I'm assuming that you have only shown on subset of your code for this function as it isn't clear how i gets updated on each iteration of the loop. When would you exit this loop?