Don't do anything with any CreateFcn() functions. Put the code to load the strings into the popup in your pushbutton callback that reads in your data. Let's say that str43 is the name of your structure with 43 fields in it. And let's say the field called "field1" is the field that contains the data. And let's say you want to get that field from the second structure in your 3x1 structure array. You can get it by doing
field1 = str43(2).field1;
Now, you need to convert the rows of field1 into strings. How to do that depends on what kind of variable field1 is. If field1 is a cell array of strings, then you can do
handles.popupmenu1.String = field1;
If it's a row or column vector of floating point numbers, then you can do
for row = 1 : size(field1)
popupStrings{k} = sprintf('%f', field1(k)); % Convert number to string.
end
% Send cell array to the popup comtrol:
handles.popupmenu1.String = popupStrings;
If field1 is some other kind of variable, then you're going to have to figure out how you want it to appear in your popup list and do something to make the cell array of strings.
