structure containing empty string arrays

Hi, I'm using a structure to hold some text data. The fields of the structure are initialised as cells. However it seems that if the field is left empty then the value is converted to a double meaning I can't consistently index that value. Do I need to specifically test each value or is there a better way? Thanks

x=struct('a',{},'b',{});
x(1).a={'abc' 'bbc'};
x(1).b={'cbc'};
x(2).a={'dbc'};

for iloc=1:2
sprintf('%s,%s\n',...
   x(iloc).a{:},...
   x(iloc).b{:})
end

Answer 1

[Azzi Abdelmalek]

You can use

x=struct('a',{''},'b',{''});

Edit

n=10;
v=arrayfun(@(x) {''},1:n,'un',0)
a=struct('a',v,'b',v)

[Tom Wright]

This nearly works, sadly x(2).b is now type 'char' and x(2).b{:} still doesnt work.

[Azzi Abdelmalek]

Then use

x=struct('a',{'','',''},'b',{'','',''});

You did not specify the length.

[Azzi Abdelmalek]

For general case you can use

n=10
v=arrayfun(@(x) '',1:n,'un',0)
a=struct('a',v,'b',v)

[Tom Wright]

Hmm, just spotted a typo in my original question, now corrected. I can't preallocate the structure completely since I don't know how many values I'm going to find. The solution

x=struct('a',{'','',''},'b',{'','',''});

also doesn't work as required

type(x(2).b) = char

[Azzi Abdelmalek]

Ok, use this, it should work

n=10;
v=arrayfun(@(x) {''},1:n,'un',0)
a=struct('a',v,'b',v)

Answer 2

[Sean de Wolski]

You should be able to use repmat() to create a cell array of empty strings:

C = repmat({''},10,10)

And then feed this into the struct() constructor.

[Sean de Wolski]

@Tom, works fine for me:

C = repmat({''},10,10)
S = struct('C',C)
S(10,1).C = 'pi'