more effective way of reading file with streamreader?

[VMI]

I normally use the following sequence of code to read from a file. Is there
any other way I can do it where I don't have to do that first ReadLine()
that's outside of the loop? But if I don't do that, how am I going to
process that first line?

myReader.Open();
myVar = myReader.ReadLine(); //for first line of file
while (myVar != null)
{
/* do what I have to do with myVar */
myVar = myReader.ReadLine();
}

Thanks.

[Jon Skeet [C# MVP]]

VMI <vo******@yahoo.com> wrote:

I normally use the following sequence of code to read from a file. Is there
any other way I can do it where I don't have to do that first ReadLine()
that's outside of the loop? But if I don't do that, how am I going to
process that first line?

myReader.Open();
myVar = myReader.ReadLine(); //for first line of file
while (myVar != null)
{
/* do what I have to do with myVar */
myVar = myReader.ReadLine();
}

My normal code is something like:

string line;

while ( (line=myReader.ReadLine()) != null)
{
// Do something with line
}

--
Jon Skeet - <sk***@pobox.com>
http://www.pobox.com/~skeet
If replying to the group, please do not mail me too

[Martin]

Hi,

You could try

myReader.Open();

while ( (myVar = myReader.ReadLine()) != null)
{
/* do what I have to do with myVar */
}

Or maybe:

myReader.Open();
do
{
/* do what I have to do with myVar */
myVar = myReader.ReadLine();
} while (myVar != null);
Martin

VMI wrote:

I normally use the following sequence of code to read from a file. Is there
any other way I can do it where I don't have to do that first ReadLine()
that's outside of the loop? But if I don't do that, how am I going to
process that first line?

myReader.Open();
myVar = myReader.ReadLine(); //for first line of file
while (myVar != null)
{
/* do what I have to do with myVar */
myVar = myReader.ReadLine();
}

Thanks.

[VMI]

I didn't know that was possible. Thanks.

"Jon Skeet [C# MVP]" <sk***@pobox.com> wrote in message
news:MP************************@msnews.microsoft.c om...

VMI <vo******@yahoo.com> wrote:

I normally use the following sequence of code to read from a file. Is
there
any other way I can do it where I don't have to do that first ReadLine()
that's outside of the loop? But if I don't do that, how am I going to
process that first line?

myReader.Open();
myVar = myReader.ReadLine(); //for first line of file
while (myVar != null)
{
/* do what I have to do with myVar */
myVar = myReader.ReadLine();
}

My normal code is something like:

string line;

while ( (line=myReader.ReadLine()) != null)
{
// Do something with line
}

--
Jon Skeet - <sk***@pobox.com>
http://www.pobox.com/~skeet
If replying to the group, please do not mail me too

[Jon Skeet [C# MVP]]

VMI <vo******@yahoo.com> wrote:

I didn't know that was possible. Thanks.

Just bear in mind that *usually* it's a really bad idea to include
assignment in the middle of something else. However, it's a common
idiom in this case - not just for reading lines, but also reading
chunks of data.

--
Jon Skeet - <sk***@pobox.com>
http://www.pobox.com/~skeet
If replying to the group, please do not mail me too

[Adam Clauss]

"Martin" <ma**********************@eircom.NOSPAM.net> wrote in message news:Or**************@TK2MSFTNGP14.phx.gbl...

myReader.Open();
do
{
/* do what I have to do with myVar */
myVar = myReader.ReadLine();
} while (myVar != null);

Except that where you have "/* do what I have to do with myVar */" - myVar at that point has no value (at least, not one that
has been read from the file).

--
Adam Clauss
ca*****@tamu.edu

[Martin]

Thats the problem with cut & paste :-) I pasted the comment in the wrong
place. Sorry.

Martin

Adam Clauss wrote:

"Martin" <ma**********************@eircom.NOSPAM.net> wrote in message
news:Or**************@TK2MSFTNGP14.phx.gbl...

myReader.Open();
do
{
/* do what I have to do with myVar */
myVar = myReader.ReadLine();
} while (myVar != null);

Except that where you have "/* do what I have to do with myVar */"
- myVar at that point has no value (at least, not one that has been read
from the file).

[James Curran]

Nope, still doesn't work... Move the comment to after the ReadLine(),
and on the last pass, you're working on a null string.

--
Truth,
James Curran
Home: www.noveltheory.com Work: www.njtheater.com
Blog: www.honestillusion.com Day Job: www.partsearch.com
(note new day job!)
"Martin" <ma**********************@eircom.NOSPAM.net> wrote in message
news:u1**************@TK2MSFTNGP11.phx.gbl...

Thats the problem with cut & paste :-) I pasted the comment in the wrong
place. Sorry.

Martin

Adam Clauss wrote:

"Martin" <ma**********************@eircom.NOSPAM.net> wrote in message
news:Or**************@TK2MSFTNGP14.phx.gbl...

myReader.Open();
do
{
/* do what I have to do with myVar */
myVar = myReader.ReadLine();
} while (myVar != null);

Except that where you have "/* do what I have to do with myVar */"
- myVar at that point has no value (at least, not one that has been read
from the file).

[C# Learner]

James Curran <Ja*********@mvps.org> wrote:

Nope, still doesn't work... Move the comment to after the ReadLine(),
and on the last pass, you're working on a null string.

myReader.Open();
while (true) {
MyVar myVar = myReader.ReadLine();
if (myVar == null) {
break;
}

// do something with myVar
}

Some might immediately frown at this because we're exiting from the loop
with 'break', but practically, it's simple and readable since it has only
one exit point.

A benefit of this construct is that the variable can be declared in the
inner-most block in which it's required.

Note that declaring the variable inside of the loop is just as performant
as declaring it outside of the loop.