User defined function in for loop

I have created a loop to loop through a series of csv files and perform functions. The code I wrote is below:

file=('list of my files')
for i = 1:length(file)  
   csv = readtable(file{i});
    Date=csv{1,2}
    D(i,:)=Date %% I get a cell array with the dates from each file
end

The code that I wrote works but I need to transform it into a user-defined function. I have tried creating the function below. However, when I call the function I do not get the required results. Am I creating the function incorrectly?

    function [csv,D] = read_function(i,file,a,b);

csv = readtable(file{i});
 Date=csv{a,b};
    D(i,:)=Date
    end
    
    %%% In a new window I call the function like this
   file=('list of my files')
    for i = 1:length(file)  
    a=1;
  b=2; 
  [csv,D] = read_function(i,file,a,b);
    end

[VBBV]

Convert the csv variable to double and then pass it as function output argument. csv is table array and not double

[Doron Joffe]

Thank you very much. Would I add a line to the function which states csv=table2array(csv) ?

It still seems to give problems when i try that.