MATLAB: About write in file

Hi everyone: I have a exist file named as 'data.txt', and I want to write data into the file in every loop; but the update data always overwrite on the previous, how can I avoid this problem and write data in file as the size of n*2; my code as follow: the size of matrix h is n*2;
for i = 1 : 10
fid = fopen('data.txt','w+');
fprintf(fid,'%d\n',h(i,:));
fclose(fid);
end
Thank you so much!

Best Answer

for i = 1 : 10
fid = fopen('data.txt','at');
fprintf(fid,'%d\n',h(i,:));
fclose(fid);
end