[vb.net] count number of lines in a textfile

[John Veteran]

  Visual Basic .NET said:

Dim line(1000), txt As String

Dim x As Integer = 0

Dim file As System.IO.StreamReader

file = New System.IO.StreamReader(OpenFileDialog1.FileName)

Do

? ? txt = file.ReadLine()

? ? line(x) = txt

? ? x += 1

Loop Until txt Is Nothing

currently i'm using this to read a text file and put each line of text in an array of strings (i need to parse the strings later). this works great, but i have to declare line() with an index, or redim it later with an index of the number of lines the file contains. this code works for files up to 1001 lines long (arrays start at 0) but files larger than that cause an error. my problem lies in that i can't find the number of lines without doing something like this first:

  Visual Basic .NET said:

Do

? ? txt = file.ReadLine()

? ? x += 1

Loop Until txt Is Nothing

ReDim line(x)

x = 0 'set x to zero for start of next loop

this would work, but i would be reading the file twice, which takes time. sure, most text files aren't so big that you would notice a pause, but i want to do:pt right :p how would i get the number of lines in a text file? searching on MSDN doesn't bring up much about this with the streamreader class, so i don't know what to do...

[noll3095]

So your problem is the size of the array? Have you tried using an ArrayList instead? It should automatically grow as you fill it.

[figgy]

You don't need to load the whole file all at once into memory.

Just check for number of VbCr (ascii 13) charaters in the text file.

This will give you the number of lines in the file.

If the last character of the file is not VbCr or VbLf (ascii 10) then add 1 to the total count.

[John Veteran]

figgy: wouldn't i have to read the file twice to do that though? i don't want to read it twice unless there's no other way :/

noll: i'll look into arraylists, i haven't heard of those...

[noll3095]

  gameguy said:

noll: i'll look into arraylists, i haven't heard of those...

Yes, check out all the Collections classes. I can't remember the last time I used a normal array for much of anything. I was fortunate enough to have a professor for Java who taught us these and made us rewrite many parts of the Java Collections Framework (which mostly works the same in .NET) so I've used them extensively knowing how they work.

[idbuythatforadollar]

if you just want the contents of the file and dont worry too much about having it line by line, you could just use streamreader.readtoend() if i remember correctly.

[John Veteran]

i need it line by line, otherwise i'd do that.

using this code, i get an error saying "index was out of range. must be non-negative number and less than the size of the collection."

  Quote

Dim line As New ArrayList()

Dim txt As String

Dim x As Integer = 0

Dim file As System.IO.StreamReader

file = New System.IO.StreamReader(OpenFileDialog1.FileName)

Do

? ? txt = file.ReadLine()

? ? line(x) = txt 'code crashes on this line

? ? x += 1

Loop Until txt Is Nothing

:blink:blink: the index IS a non-negative number less than the size of the collection (default capacity for an ArrayList is 16, right?) x is zero, which satisfies both conditions, so what's the pro:huh: :huh: it's happening the first time it loops, when x is zero. and it should grow when it needs to anyway, r:unsure:nsure:

[John Veteran]

nevermind, i fixed it. i had to use line.Insert(x, txt) instead of treating it as an array.

fixed code:

  Quote

Do

? ? txt = file.ReadLine()

? ? line.Insert(x, txt) 'Insert(index As Integer, value As Object)

? ? x += 1

Loop Until txt Is Nothing

Edited November 2, 2003 by gameguy