num2str gives error as 'from struct to double conversion is not possible'

Hello everyone. I have a number of data files(pdbs) named as 1.pdb 2.pdb 3.pdb etc.. so I want to read all of them in a loop. Can someone explain why this does not work?

pdb= zeros;
for i=1:1000;
   pdb(i,1) = pdbread([int2str(i) '.pdb']);
   i=i+1;
end

it says 'Conversion to double from struct is not possible.'

thank you

Answer 1

[madhan ravi]

pdb= cell(1e3, 1);
for ii = 1 : 1e3;
    pdb{ii} = pdbread(sprintf('%d.pdb', ii));
end

[Selma Nur Keskin]

Thank you sir!