# Creating variables in a foor loop using num2str

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Jiri Kovar on 23 Nov 2022
Edited: Stephen23 on 8 Dec 2022
Hi,
title probably says it all. I want to create variables according to the i in the loop. I just don't even know if I can incorporate the function (I've already tried num2str, eval, evalc, sprintf) into variable definition. Below is a non-working code just to illustrate what I mean to do (hopefully). This example is just for 3 different variables but later on, I need to do this for about 60 more variables. I just cannot quite put my hand on the right formulation of the loop.
%%% years_10 = [xvalues, yvalues]... n*2 matrices
for i=10:10:30
end
##### 2 CommentsShowHide 1 older comment
Stephen23 on 8 Dec 2022
Edited: Stephen23 on 8 Dec 2022
The easy, simple, and very efficient approach is to use indexing into one array, e.g. a cell array or structure array.
Using indexing is shown in the MATLAB documentation:

William Rose on 23 Nov 2022
Edited: William Rose on 23 Nov 2022
[edit: change "v" to "s" in my description, to match the code]
N=50;
for i=10:10:N, s.(strcat('a',num2str(i)))=i^2; end
disp(s)
a10: 100 a20: 400 a30: 900 a40: 1600 a50: 2500
creates a structure s with fields a10, a20, ..., a50. Each one equals a scalar. You could initialize each one to be a vector or array, if you prefer.
William Rose on 8 Dec 2022
@Jiri Kovar, you're welcome.

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