I have problem with empty string B in this code

   if true
    [a1,a2]=unique(c');%c is two dimension array  
[d1 idx]=sort(a2);
a1=a1(idx);
for ii=1:length(a1)
B{1,ii}=a1(ii);
[r c]=find(a==a1(ii));
for jj=1:length(r)
B{jj+1,ii}=['(',num2str(r(jj)),',', num2str(c(jj)),')'];
end
end
  end
  end

when i want to store B in text file error empty string why ?

[Jan]

Please post the complete error message. "When I want to store B in a text file" does not allow to understand, what you are doing exactly.

[Image Analyst]

Give a small example of c so we can run your code. My guess is that you are never entering the for loop to assign B, however in that case it should say that B is undefined, not empty. How are you doing the write to the file? With fprintf()???