Read/Writing to the same file

[Thomas Adam]

Hi All,

I've been lurking on this list for a while, and I have a basic question
that I'm hoping someone can help answer.

I have read the FAQ regarding file I/O, and I am still having problems.
Basically, I'm opening a file like this:

myfile = File.open("/home/n6tadam/the_file", "r+")
arr[]

arr = myfile.readlines()
#change contents of arr

myfile.rewind()
myfile.print arr
myfile.close()

but still the file has not updated. Any ideas why? Also, when you want to
do in-place editing of the file, do you have to read the file into an
array first?

Hope that's not too confusing,

-- Thomas Adam


=====
Thomas Adam

"The Linux Weekend Mechanic" -- www.linuxgazette.com

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[mark]

Hi All,

I've been lurking on this list for a while, and I have a basic question
that I'm hoping someone can help answer.

I have read the FAQ regarding file I/O, and I am still having problems.
Basically, I'm opening a file like this:

I can see two problems with the program

myfile = File.open("/home/n6tadam/the_file", "r+")
arr[]

This line causes an error since arr hasn't been initialised at this point

arr = myfile.readlines()
#change contents of arr

myfile.rewind()
myfile.print arr

This will put all the elements of arr on one line. If you want each element to
appear on a seperate line then you should use

myfile.puts arr

myfile.close()

aside from those two points the program works as expected.

but still the file has not updated. Any ideas why? Also, when you want to
do in-place editing of the file, do you have to read the file into an
array first?

Hope that's not too confusing,

-- Thomas Adam

Hope that helps

Best Regards

Mark Sparshatt