determining end of file

[cj]

I'm reading a file line by line using

line = StreamReader.Re adLine

and normally I

Do While Not line = Nothing

But, this file has a lot of blank lines. How do I determine if I'm at
the end of the file when there are lots of blank lines in the file?

[GhostInAK]

Re: determining end of file

Hello cj,

a blank line should have a value of string.empty, the EOF should have a value
of Nothing.

-Boo

I'm reading a file line by line using
>
line = StreamReader.Re adLine
>
and normally I
>
Do While Not line = Nothing
>
But, this file has a lot of blank lines. How do I determine if I'm at
the end of the file when there are lots of blank lines in the file?
>

[Herfried K. Wagner [MVP]]

Re: determining end of file

"cj" <cj@nospam.nosp amschrieb:

I'm reading a file line by line using
>
line = StreamReader.Re adLine
>
and normally I
>
Do While Not line = Nothing
>
But, this file has a lot of blank lines. How do I determine if I'm at
the end of the file when there are lots of blank lines in the file?

Use 'Do While Line IsNot Nothing' or 'Do While Not Line Is Nothing'.

--
M S Herfried K. Wagner
M V P <URL:http://dotnet.mvps.org/>
V B <URL:http://dotnet.mvps.org/dotnet/faqs/>

[iwdu15]

Re: determining end of file

you could also do

Dim sr As New StreamReader(.. .)

While sr.Peek -1

SomeStringVaria ble = sr.ReadLine()

End While

--
-iwdu15

[Walter Wang [MSFT]]

RE: determining end of file

Hi cj,

It's because Visual Basic runtime usually evaluates Nothing as an empty
string (""). Following code prints "True":

Dim s As string = ""
Console.WriteLi ne(s = Nothing)

Since StreamReader.Re adLine() returns null when the file reaches to end, we
need to use Is or IsNot operator to determine whether or not an object is
null.

For more information, please refer to following MSDN Library:

#Is Operator (Visual Basic)
http://msdn2.microsoft.com/en-us/library/kb136x1y.aspx

#IsNot Operator
http://msdn2.microsoft.com/en-us/library/t3bat82c.aspx

#Nothing and Strings in Visual Basic
http://msdn2.microsoft.com/en-us/library/ms233957.aspx

Please reply to let us know whether or not you need further information.
Thank you.

Sincerely,
Walter Wang (wawang@online. microsoft.com, remove 'online.')
Microsoft Online Community Support

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[cj]

Re: determining end of file

So I thought. However apparently "" = nothing but "" isnot nothing. I
still don't quite get it but Herfried was right on his suggestion
although w/o Walters' explanation I'd have no clue why.

GhostInAK wrote:

Hello cj,
>
a blank line should have a value of string.empty, the EOF should have a
value of Nothing.
>
-Boo
>

>I'm reading a file line by line using
>>
>line = StreamReader.Re adLine
>>
>and normally I
>>
>Do While Not line = Nothing
>>
>But, this file has a lot of blank lines. How do I determine if I'm at
>the end of the file when there are lots of blank lines in the file?
>>

>
>

[cj]

Re: determining end of file

This is confusing. "" = Nothing but "" IsNot Nothing.

So what we're saying is "" is equivalent to Nothing but it is not the
same thing as Nothing?


Walter Wang [MSFT] wrote:

Hi cj,
>
It's because Visual Basic runtime usually evaluates Nothing as an empty
string (""). Following code prints "True":
>
Dim s As string = ""
Console.WriteLi ne(s = Nothing)
>
Since StreamReader.Re adLine() returns null when the file reaches to end, we
need to use Is or IsNot operator to determine whether or not an object is
null.
>
For more information, please refer to following MSDN Library:
>
#Is Operator (Visual Basic)
http://msdn2.microsoft.com/en-us/library/kb136x1y.aspx
>
#IsNot Operator
http://msdn2.microsoft.com/en-us/library/t3bat82c.aspx
>
#Nothing and Strings in Visual Basic
http://msdn2.microsoft.com/en-us/library/ms233957.aspx
>
Please reply to let us know whether or not you need further information.
Thank you.
>
Sincerely,
Walter Wang (wawang@online. microsoft.com, remove 'online.')
Microsoft Online Community Support
>
=============== =============== =============== =====
Get notification to my posts through email? Please refer to
http://msdn.microsoft.com/subscripti...ult.aspx#notif
ications. If you are using Outlook Express, please make sure you clear the
check box "Tools/Options/Read: Get 300 headers at a time" to see your reply
promptly.
>
Note: The MSDN Managed Newsgroup support offering is for non-urgent issues
where an initial response from the community or a Microsoft Support
Engineer within 1 business day is acceptable. Please note that each follow
up response may take approximately 2 business days as the support
professional working with you may need further investigation to reach the
most efficient resolution. The offering is not appropriate for situations
that require urgent, real-time or phone-based interactions or complex
project analysis and dump analysis issues. Issues of this nature are best
handled working with a dedicated Microsoft Support Engineer by contacting
Microsoft Customer Support Services (CSS) at
http://msdn.microsoft.com/subscripti...t/default.aspx.
=============== =============== =============== =====
>
This posting is provided "AS IS" with no warranties, and confers no rights.
>

[cj]

Re: determining end of file

Thanks for the input but right now I feel more comfortable the other way.

iwdu15 wrote:

you could also do
>
Dim sr As New StreamReader(.. .)
>
While sr.Peek -1
>
SomeStringVaria ble = sr.ReadLine()
>
End While
>

[cj]

Re: determining end of file

Thanks that works, you might want to see my reply to Walter.

Herfried K. Wagner [MVP] wrote:

"cj" <cj@nospam.nosp amschrieb:

>I'm reading a file line by line using
>>
>line = StreamReader.Re adLine
>>
>and normally I
>>
>Do While Not line = Nothing
>>
>But, this file has a lot of blank lines. How do I determine if I'm at
>the end of the file when there are lots of blank lines in the file?

>
Use 'Do While Line IsNot Nothing' or 'Do While Not Line Is Nothing'.
>

[Walter Wang [MSFT]]

Re: determining end of file

Hi cj,

I understand your concerns.

As a rule of thumb, you need to remember to use Is or IsNot to compare
object references. Normally we don't use "= Nothing" to check for null
reference.

Regards,
Walter Wang (wawang@online. microsoft.com, remove 'online.')
Microsoft Online Community Support

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