Counting lines in a file

[jabailo]

Which would be faster for counting lines in a StreamReader:

(a) iterate through a file using .ReadLine() and adding to a counter, i++

(b) doing a .ReadToEnd() and then using an IndexOf() method to count the
occurances of \r\n

(c) doing a .ReadToEnd() and using a RegEx to count the number of occurances
of \r\n

 

[wbekker]

Hi Javailo,

I would guess that option c scales better, but a small test might show
the real winner ;-)

Ward

 

[Bob Powell [MVP]]

I haven't tested but probably A for any arbitrary length of file.

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[Dmytro Lapshyn [MVP]]

Hi,

I think (b) should be the fastest, but I wouldn't expect any significant
difference between (a) and (b) since Windows does efficient disk read
buffering behind the scenes.
I think (c) should be the slowest because of RegExp.

Anyway, it's all just guessing, why don't you try all the three approaches
and post the real result here? ;-)

 

[Cor Ligthert]

Hi,

Giving my guess as well A/B ex aquo as first.



Cor

 

[Chad Z. Hower aka Kudzu]

Which would be faster for counting lines in a StreamReader:

The only way to find out is to test it, and in fact different ones may be faster depending on size and
characteristics of the file.

(a) iterate through a file using .ReadLine() and adding to a counter,
i++

This is probably the best over all considering memory considerations etc if your file is large. And
probably the fastest too.

(b) doing a .ReadToEnd() and then using an IndexOf() method to count
the occurances of \r\n

(c) doing a .ReadToEnd() and using a RegEx to count the number of
occurances of \r\n

Both of these will consume large amoutns of memory if the file is large.


--
Chad Z. Hower (a.k.a. Kudzu) - http://www.hower.org/Kudzu/
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[Ignacio Machin \( .NET/ C# MVP \)]

hi,

the first option is the way to go, unless you are 100% sure that the size of
the file in advance.

The others solutions are not portable, you should use
Environment.NewLine() instead of "\r\n"

cheers,