how to convert a column of cells into string?

when i try my code ( search for a word in a cells of column), i use :

% search for "battery" in column 52th
B=~cellfun('isempty',regexp(alldata(:,52),'BATTERY'))

i got an error : All cells must be strings.

B=~cellfun('isempty',regexp(alldata(:,52),'BATTERY'))

how i can solve this?

note: the column contain a texts but some cells is empty or contain NaN

Answer 1

[per isakson]

NaN is double

>> class( nan )
ans =
double

replace Nan by '' (empty string)

>> alldata = {'abc', nan, 'def'}
alldata = 
    'abc'    [NaN]    'def'
>> alldata{ not( cellfun( @ischar, alldata ) ) } = '';
>> alldata
alldata = 
    'abc'    ''    'def'

[Amr Hashem]

how i can do a for loop on a column of cells which some are not string to make them string

[per isakson]

>> alldata{ not( cellfun( @ischar, alldata ) ) } = '';

does that. Why use a loop?

any_string_value = 'abc';
for jj = 1 : length( alldata )
    if not( ischar( alldata{jj} ) )
        alldata{jj} = any_string_value;
    end 
end