What is the fastest way to count lines in a text file?

[mesterak]

I want to very quickly count the number of lines in text files without having
to read each line and increment a counter. I am working in VB.NET and C#.
Does anyone have a very fast example on how to do this?

Thanks,

Matt

[Cor Ligthert [MVP]]

Mesterak,

In different test in these newsgroups have showed that just looping through
the file using the string as a Char array (not testing on a string however
testing on a char) and testing on the linebreack char is mostly the fastest
method.

I hope this helps,

Cor

[mesterak]

Can you provide a code example else point me to the relevant posts?

"Cor Ligthert [MVP]" wrote:

Mesterak,

In different test in these newsgroups have showed that just looping through
the file using the string as a Char array (not testing on a string however
testing on a char) and testing on the linebreack char is mostly the fastest
method.

I hope this helps,

Cor

[Vadym Stetsyak]

Maybe using regular expression can be fast solution ( for large text
files ).
You will count matches for \r\n or \n

--
Vadym Stetsyak aka Vadmyst
http://vadmyst.blogspot.com

"mesterak" <me******@discu ssions.microsof t.com> wrote in message
news:C9******** *************** ***********@mic rosoft.com...

I want to very quickly count the number of lines in text files without
having
to read each line and increment a counter. I am working in VB.NET and C#.
Does anyone have a very fast example on how to do this?

Thanks,

Matt

[Cor Ligthert [MVP]]

Here is one message thread

http://groups.google.com/group/micro...5c33cc87237dbf

Be aware that in this case the samples provided by Jay about the characters
are the fastest and not the VB Find which it is if it is about strings.

I hope this helps,

Cor

[mesterak]

I tried the following which did not seem to work:

strContents = Regex.Replace(s trContents, "\r{0,}\n+" , vbCrLf)
myArrayList.Add Range(strConten ts.Split(CType( vbCrLf, Char)))
"Vadym Stetsyak" wrote:

Maybe using regular expression can be fast solution ( for large text
files ).
You will count matches for \r\n or \n

--
Vadym Stetsyak aka Vadmyst
http://vadmyst.blogspot.com

"mesterak" <me******@discu ssions.microsof t.com> wrote in message
news:C9******** *************** ***********@mic rosoft.com...

I want to very quickly count the number of lines in text files without
having
to read each line and increment a counter. I am working in VB.NET and C#.
Does anyone have a very fast example on how to do this?

Thanks,

Matt

[Jon Skeet [C# MVP]]

Vadym Stetsyak <va*****@ukr.ne t> wrote:

Maybe using regular expression can be fast solution ( for large text
files ).
That's very unlikely, IMO.
You will count matches for \r\n or \n

And how will you provide the text for the regular expression to match?
As far as I'm aware, you can't provide regular expressions with
TextReaders - you have to provide them with strings.

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

[Cor Ligthert [MVP]]

Mesterak,

In those messages I show show you is using the split and the regex the
farmost slowest method to count lines.

Cor

[mesterak]

So how can I count the lines of the file without loading the whole file into
memory as a string and counting lines?

"Jon Skeet [C# MVP]" wrote:

Vadym Stetsyak <va*****@ukr.ne t> wrote:

Maybe using regular expression can be fast solution ( for large text
files ).

That's very unlikely, IMO.

You will count matches for \r\n or \n

And how will you provide the text for the regular expression to match?
As far as I'm aware, you can't provide regular expressions with
TextReaders - you have to provide them with strings.

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

[Jon Skeet [C# MVP]]

mesterak <me******@discu ssions.microsof t.com> wrote:

So how can I count the lines of the file without loading the whole file into
memory as a string and counting lines?

By reading chunks at a time (using StreamReader) and counting '\n'
occurrences.

Here's some sample code:

using System;
using System.IO;

class Test
{
static int CountLines (TextReader reader)
{
char[] buffer = new char[32*1024]; // Read 32K chars at a time

int total=1; // All files have at least one line!

int read;
while ( (read=reader.Re ad(buffer, 0, buffer.Length)) > 0)
{
for (int i=0; i < read; i++)
{
if (buffer[i]=='\n')
{
total++;
}
}
}
return total;
}

static void Main(string[] args)
{
foreach (string file in args)
{
using (StreamReader reader = new StreamReader(fi le))
{
Console.WriteLi ne ("{0}: {1} lines", file,
CountLines(read er));
}
}
}
}

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