[Tutor] File operation query

[Reuben]

Thanks everyone for the suggestion.

At the moment, file.flush() resolves the problem - but I will also give a
thought to suggestions provided by other members in this email chain.

Regards,
RD

On Thu, Oct 15, 2015 at 11:05 PM, Alan Gauld <alan.gauld at btinternet.com>
wrote:

> On 15/10/15 17:00, Reuben wrote:
>
> I need some clarification for below code. In line 2 of below code snippet,
>> I have provided read and write permission.
>>
>
> Thios is nearly always a bad idea and leads to all sorts of complications,
> as you are discovering!
>
> string input as requested in line 1 - when I try to open "check.txt" file
>> after running the script, it is always empty - it does not display the
>> user
>> input provided.
>>
>
> Its not empty but you are positioned after the text you inserted.
>
>
>> input1 = raw_input("Input1:")
>> file = open("check.txt", "r+")
>>
>> file.write(input1 + "\n")
>>
>
> This writes your text at the start of the file
> (incidentally overwriting anything that was there
> from the previous run). It leaves the file cursor
> at the end of your txt.
>
> for line in file:
>>          print line
>>
>
> This tries to read from the file cursor to the end of the file.
> But you are already at the end so it returns nothing.
> You need to do a seek(0) to put the cursor back to the start.
> Then remember to go back to the end before trying to write again.
> I told you it was more complicated!
>
> print file.close()
>>
>
> printing close() is not useful.
>
> HTH
> --
> Alan G
> Author of the Learn to Program web site
> http://www.alan-g.me.uk/
> http://www.amazon.com/author/alan_gauld
> Follow my photo-blog on Flickr at:
> http://www.flickr.com/photos/alangauldphotos
>
>
>
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