MATLAB: Concatenate cell

Question

i have a cell (symbol {} on the variable list) with a=('kkk', 'lll', 'xxx', 'jjj.xls')

and i want to concatenate a so that i can have

b = ('kkk_lll_xxx_jjj.xls')

thank you

Answer 1

a={'kkk', 'lll', 'xxx', 'jjj.xls'}';
out = [a(:)';repmat({'_'},1,numel(a))];
out = [out{:}];
out = out(1:end-1);

variant 2

out = cell(1,2*numel(a)-1);
out(1:2:end) = a;
out(2:2:end) = {'_'};
out = [out{:}];