Re: [Tutor] Question about reading from a file.
On 07/08/2012 13:37, Ramchandra Apte wrote: Imagine a book. .read(num) reads a page of the book Now if you call again it goes to the next page. Please don't top post. This is now the fourth time you've been asked. -- Cheers. Mark Lawrence. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Question about reading from a file.
> > Imagine a book. > .read(num) reads a page of the book Now if you call again it goes to the next page. > Tutor maillist - Tutor@python.org > To unsubscribe or change subscription options: > http://mail.python.org/mailman/listinfo/tutor > ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Question about reading from a file.
On Tue, Aug 7, 2012 at 5:12 AM, Mark Lawrence wrote: > On 04/08/2012 22:51, Brad Dutton wrote: >> >> I recently discovered how to read from a file but I've having some trouble >> with it. I made a short example program that goes like this: >> >> >> 1. fob = open('c:/python27/a.txt', 'r') >> 2. >> 3. print fob.read() >> 4. print fob.read() >> >> >> When it runs it returns this: >> >> >> 1. Hey now brown cow >> 2. >> >> It's like it forgets how to read after the first time. This has left me >> very confused. Could you offer any reason why this might be happening? You need to understand some basic concepts about what a file is in computer programming. The other posters have helped you out. You can find out more here: http://docs.python.org/tutorial/inputoutput.html#methods-of-file-objects or spend an hour or so (at least) with the results from googling 'python file operation example' good luck >> >> >> >> ___ >> Tutor maillist - Tutor@python.org >> To unsubscribe or change subscription options: >> http://mail.python.org/mailman/listinfo/tutor >> > > Further to Peter Otten's answer you make want to take a look at readline or > readlines, or check into file iteration. Depends on what you're trying to > achieve :) > > -- > Cheers. > > Mark Lawrence. > > > ___ > Tutor maillist - Tutor@python.org > To unsubscribe or change subscription options: > http://mail.python.org/mailman/listinfo/tutor -- Joel Goldstick ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Question about reading from a file.
On 04/08/2012 22:51, Brad Dutton wrote: I recently discovered how to read from a file but I've having some trouble with it. I made a short example program that goes like this: 1. fob = open('c:/python27/a.txt', 'r') 2. 3. print fob.read() 4. print fob.read() When it runs it returns this: 1. Hey now brown cow 2. It's like it forgets how to read after the first time. This has left me very confused. Could you offer any reason why this might be happening? ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor Further to Peter Otten's answer you make want to take a look at readline or readlines, or check into file iteration. Depends on what you're trying to achieve :) -- Cheers. Mark Lawrence. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Question about reading from a file.
Brad Dutton wrote: > I recently discovered how to read from a file but I've having some trouble > with it. I made a short example program that goes like this: > > >1. fob = open('c:/python27/a.txt', 'r') >2. >3. print fob.read() >4. print fob.read() > > When it runs it returns this: > > >1. Hey now brown cow >2. > > It's like it forgets how to read after the first time. This has left me > very confused. Could you offer any reason why this might be happening? The open file, 'fob' maintains a pointer into the file that is moved by read operations: >>> fob = open("a.txt") >>> fob.read(3) 'Hey' >>> fob.read(3) ' no' >>> fob.read(3) 'w b' If you call the read method without argument the complete (remaining) file is read and following read calls will not give any data to read: >>> fob.read() 'rown cow\n' >>> fob.read() '' Most of the time the best approach is to open a new file >>> for i in range(3): ... with open("a.txt") as f: print f.read().strip() ... Hey now brown cow Hey now brown cow Hey now brown cow but it is also possible to move the pointer back to the beginning to the file (or elsewhere): >>> fob.seek(4) >>> fob.read() 'now brown cow\n' >>> fob.seek(0) >>> fob.read() 'Hey now brown cow\n' ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor