reconstruct text file after importdata?

Hi,

I am using matlab to rewrite a .txt file after I change parts of the file. My function reads in a .txt file using the importdata function. The text file is a csound file, rather a file that can be read and played by the sound synthesis engine csound. However, there are problems with these files, and I am using matlab to fix those problems in a programmatic way. The importdata function seems to work perfectly because it splits my file up into textdata that I don't need to change, and data that I do. So I use importdata, then I do computations on the numerical data to change it to what I want, and now I need to put it back together. However, there doesn't seem to be a complimentary function to the importdata function. Or is there? Heres some code:

    function tienotes(infile, outfilename)

    % FUNCTION VARIABLES
    inID = fopen(infile, 'r');
    outID = fopen(outfilename, 'wb');

    % GET HEARDERLINES OF INPUT FILE
    HEADERLINES = 0;
    line = fgetl(inID); % returns current line of file
    while ischar(line)
        if numel(line) == 0
            HEADERLINES = HEADERLINES + 1;
        elseif line(1) == 'i'
            break
        else
            HEADERLINES = HEADERLINES + 1;
        end
    line = fgetl(inID);
    end

    % IMPORT THE FILE
    newData = importdata(infile, ' ', HEADERLINES);
    % Create new variables in the base workspace from those fields.
    vars = fieldnames(newData);
    for i = 1:length(vars)
        assignin('base', vars{i}, newData.(vars{i}));
    end

    % TIE NOTES
    data = newData.data;
    [numrows, numcols] = size(data);
    for m = 1:numrows
        for n = m:numrows
            if(data(m,1) + abs(data(m,2)) ==  data(n,1)) % check if start time 
                % plus duration in one row is equal to start time of another
                % row, abs for if note is already tied
                if(data(m,3) == data(n,3)) % check if note indeces are the same
                    if(data(m,5) == data(n,5)) % check if chan #s are the same
                        if(sign(data(m,2)) == 1) % if positive value
                            data(m,2) = -(data(m,2) + data(n,2)); % neg for tie  
                        elseif(sign(data(m,2)) == -1) % if negative value, then
                            % its already tieing some notes, but you cant add
                            % to the negative, so you need to subtract!
                            data(m,2) = data(m,2) - data(n,2);
                        end
                    end
                end
            end
        end
    end

    % PUT NEW DATA INTO OUTPUT FILE
    % ???

    % CLOSE STUFF
    fclose(inID);
    fclose(outID);
    end