Uppercase string from the cell array

I have a cell array a = {'AA_DFA_DD' ,'DSFA_dfaf' ,'DDDD' , 'DFE1' ,'dfs_DD'}

How can extract only the upper case string from the cell array

my answer should be {'AA_DFA_DD',[],'DDDD','DFE1',[]}

How can i do this?

Thanks a lot

[Stephen23]

+1 for a clear question with input and output examples.

Answer 1

[Stephen23]

regexp(a,'^[^a-z]+$','match')

[Gopalakrishnan venkatesan]

It works well

Can give me the small explanation of expression

Thanks a lot

[Stephen23]

^          % match start of string
 [^a-z]    % match any character EXCLUDING lower-case
       +   % repeated one or more times
        $  % match end of string

These are all explained in the documentation:

http://www.mathworks.com/help/matlab/matlab_prog/regular-expressions.html

Answer 2

[Azzi Abdelmalek]

out=a(cellfun(@(x,y) isequal(x,y),a,upper(a)))

or

out=cell(size(a))
idx=cellfun(@(x,y) isequal(x,y),a,upper(a))
out(idx)=a(idx)

[Gopalakrishnan venkatesan]

thanks a lot