writetable() to change header and append cell array in each row

I have a cell array made of cell array tables such that

testarray
= 1×2 cell array
{1×3 table}    {1×3 table}  

And

testarray{1}
=  1×3 table

                   Var1                     Var2      Var3     
    ___________________________________    ______    ______ 
                    '1'                      '2'       '3'
testarray{2}
=  1×3 table

                   Var1                     Var2      Var3     
    ___________________________________    ______    ______ 
                    '3'                      '4'       '5'

And desired header to be

                    col1 col2 col3

How do I use writetable() to write this in excel that looks like

col1 col2 col3
1     2     3
3     4     5

Thank you!!

Answer 1

[chlor thanks]

summary = vertcat(testarray{:});

summary.Properties.VariableNames = { col1', 'col2', 'col3'}

writetable(summary, 'summary.xlsx');

Answer 2

[Scott MacKenzie]

t1 = table({'1'}, {'2'}, {'3'});
t2 = table({'4'}, {'5'}, {'6'});
t1.Properties.VariableNames = { 'col1', 'col2', 'col3' };
testarray = {t1, t2};

writetable(testarray{1}, 'test.txt');
writetable(testarray{2}, 'test.txt', 'writevariablenames', false, 'writemode', 'append');

In the command window...

>> type test.txt

col1,col2,col3

1,2,3

4,5,6

[chlor thanks]

Thanks Scott! This will help me learn!

By the way, when I try this code it says 'writemode' is a unvalid parameter name, also t2 didnt append.

[Scott MacKenzie]

Gee, that's weird. I just re-ran the code, no problem. writetable dates to R2013a, so that's unlikely an issue. Of course, t2 did not append becuase the 2nd writetable crashed. I really don't know what the issue. If somone else reads this and has an idea, perhaps they'll weight in.