I want to write several arrays on a textfile, one for each line. How can I do this?

[textfile] is your friend.
take a look at the attached patch, to have an example.

http://www.pdpatchrepo.info/hurleur/textfile.pd

You could use [tabdump] from zexy to write the contents of an array to a list and feed that into [textfile]. Something like this maybe:

[inlet name of array]
|
[set $1, bang(
|
[tabdump]
|

|
|
[textfile]

Thank you very much!!!