print cells type in Matlab - matlab

Question

I have a cell array like:
>>text
'Sentence1'
'Sentence2'
'Sentence3'
Whenever I use
sprintf(fid,'%s\n',text)
I get an error saying:
'Function is not defined for 'cell' inputs.'
But if I put :
sprintf(fid,'%s\n',char(text))
It works but in the file appears all the sentences mixed all together like with no sense.
Can you recommend me what to do?
Whener I put text I get:
>>text
'Title '
'Author'
'comments '
{3x1} cell
That is why I can not use text{:}.

Answer 1

If you issue
sprintf('%s\n', text)
you are saying "print a string with a newline. The string is this cell array". That's not correct; a cell-array is not a string.
If you issue
sprintf('%s\n', char(text))
you are saying "print a string with a newline. The string is this cell array, which I convert to character array.". The thing is, that conversion results in a single character array, and sprintf will re-use the %s\n format only for multiple inputs. Moreover, it writes that single character array by column, meaning, all characters in the first column, concatenated horizontally with all characters from the second column, concatenated with all characters from the third column, etc.
Therefore, the approprate call to sprintf is something with multiple inputs:
sprintf(fid, '%s\n', text{:})
because the cell-expansion text{:} creates a comma-separated list from all entries in the cell-array, which is exactly what sprintf/fprintf expects.
EDIT As you indicate:, you have non-char entries in text. You have to check for that. If you want to pass only the strings into fprintf, use
fprintf(fid, '%s\n', text{ cellfun('isclass', text, 'char') })
if that {3x1 cell} is again a set of strings, so you want to write all strings recursively, then just use something like this:
function textWriter
text = {...
'Title'
'Author'
'comments'
{...
'Title2'
'Author2'
'comments2'
{...
'Title3'
'Author3'
'comments3'
}
}
}
text = cell2str(text);
fprintf(fid, '%s\n', text{:});
end
function out = cell2str(c)
out = {};
for ii = c(:)'
if iscell(ii{1})
S = cell2str(ii{1});
out(end+1:end+numel(S)) = S;
else
out{end+1} = ii{1};
end
end
end