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adding data to a text file

Asked by lowcalorie on 15 Mar 2012
i have a file called hello.txt using wordpad which contains the matrix
2 7 3
2 6 9
now i have a vector v = [1 2 3] and i want to add this vector to the hello.txt file so when i open the hello.txt file i should have
2 7 3
2 6 9
1 2 3
how can i do this

  1 Comment

Walter Roberson
on 15 Mar 2012
Duplicate is at http://www.mathworks.com/matlabcentral/answers/32377-appending-a-file

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2 Answers

Wayne King
Answer by Wayne King
on 15 Mar 2012
 Accepted Answer

You can use:
dlmwrite('FILENAME',M,'-append')
For example:
x = [2 7 3; 2 6 9];
dlmwrite('test.dat',x);
y = [1 2 3];
dlmwrite('test.dat',y,'-append');

  4 Comments

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Wayne King
on 15 Mar 2012
and you are using '-append'??? Just copy and paste my example, it works.
lowcalorie on 15 Mar 2012
if i already have a file what fopen should i be using
Walter Roberson
on 15 Mar 2012
Wayne's code is designed for the case where the file is _not_ open.
The code that opens the file is shown in your duplicate question, referenced in the above comments.

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Geoff
Answer by Geoff
on 15 Mar 2012

I remember answering an almost identical question from you the other day. It used the fopen() with the open-mode 'w' to overwrite.
To append, use the open-mode 'a'.

  2 Comments

lowcalorie on 15 Mar 2012
thats what im doing but it keeps overwriting there muct be something wrong with other parts of my script then
thanks
Walter Roberson
on 15 Mar 2012
"lowcalorie" is using WordPad to examine the file. "at" is needed instead of just "a", as WordPad is an old editor that only understands lines if they end in the combination CARRIAGE-RETURN LINEFEED which you do not get if you use only "a" permissions when you are using MS Windows.

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