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.NET Forum / Languages / VB.NET / October 2004convert nulls to spaces in file
first question... I have a flat file which unfortinuatly has columns seperated by nulls instead of spaces (a higher up company created it this way for us) is there anyway to do a readline with this and not have it affected by the null? because it is right now causes truncated data at wierd places... but as soon as i manually with a hex editor change char(00) to char(20) in the files it reads prerfectly... which leads me to my 2nd question... if you cant do what i said in the 1st question, is there a way to go through the file, convert the nulls to spaces and save it back then open it as a stream reader to read it line by line? the lines are delimited by CR+LF's thanks! Brian, I would simply open it with a System.IO.FileStream, read a buffer full of bytes, change the null bytes to AscW(" "c) then write the buffer to a second FileStream. Something like: Imports System.IO Dim input As New FileStream("input.txt", FileMode.Open) Dim output As New FileStream("output.txt", FileMode.Create) Dim buffer(1023) As Byte Dim length As Integer Do length = input.Read(buffer, 0, buffer.Length) For index As Integer = 0 To length - 1 If buffer(index) = 0 Then buffer(index) = AscW(" "c) End If Next output.Write(buffer, 0, length) Loop Until length < buffer.Length input.Close() output.Close() Note the above may not work correctly for non Ansi 8-bit encodings, however it should be easy enough to adapt. Hope this helps Jay > first question... I have a flat file which unfortinuatly has columns > seperated by nulls instead of spaces (a higher up company created it this [quoted text clipped - 6 lines] > it back then open it as a stream reader to read it line by line? the lines > are delimited by CR+LF's thanks! Hrm, how about read in the file to a string and do a split with the null char being the delimiter? I haven't tried it and don't know if it will work...but what the heck, worth a try eh? Mythran > Brian, > I would simply open it with a System.IO.FileStream, read a buffer full of [quoted text clipped - 38 lines] >> it back then open it as a stream reader to read it line by line? the >> lines are delimited by CR+LF's thanks! Mythran, Brian (the original poster) stated: >>> because it is right now causes truncated data at wierd places... Which leads me to believe something strange is going on with the encoding when you attempt to read the file into a string (an encoding is required). There may not be, or it may be something simple, why risk it, when I know the FileStream won't cause problems, especially on the sample file he provided... Reading it as bytes with FileStream will not involve any Encoding objects. I am reading pure bytes, changing pure bytes, writing pure bytes. Hence I won't be taking time to track down any potential encoding problems implied with the Brian's statement. Hope this helps Jay > Hrm, how about read in the file to a string and do a split with the null > char being the delimiter? I haven't tried it and don't know if it will [quoted text clipped - 44 lines] >>> it back then open it as a stream reader to read it line by line? the >>> lines are delimited by CR+LF's thanks! Yes, your way would work...maybe even better... What I was stating is that he reads it all into a string instead of line by line (regardless of how he reads it in....such as FileStream or whatever). Then he just splits the results based on the Null...but my way may not work anyways because the Split method may not accept DBNull.Value....but it may take Chr(x). Hrm, probably would just do it your way if it was me :P Mythran > Mythran, > Brian (the original poster) stated: [quoted text clipped - 62 lines] >>>> spaces and save it back then open it as a stream reader to read it line >>>> by line? the lines are delimited by CR+LF's thanks! Mythran, Brian is referring to a Null Char (ChrW(0)). If you look at the file he attached to one of his messages the file is fixed length records. The first couple of records have 20 or 30 zero bytes at the start of the line. The ChrW(0) are not being used for record or field delimiters per se. I would use the Split method if the file was using ChrW(0) for record or field delimiters. > What I was stating is that he reads it all into a string instead of line > by line (regardless of how he reads it in....such as FileStream or > whatever). FileStream cannot read a file into a string, it only reads Bytes. To read a file into an System.Text.Encoding object is needed, as System.Text.Encoding is used to convert the bytes in the file to Unicode which is what Strings are. StreamReader uses an Encoding object to convert the bytes to a String, if you use a FileStream you would need to create your own Encoding object & use it to convert the bytes into a String. As I stated Brian's original statement suggested that the Encoding object may have been having problems with the 20 or 30 zero bytes... Hope this helps Jay > Yes, your way would work...maybe even better... > [quoted text clipped - 73 lines] >>>>> spaces and save it back then open it as a stream reader to read it >>>>> line by line? the lines are delimited by CR+LF's thanks! Ahh, didn't look at the file...but according to his first post, the columns are separated by Null. Which I read as "ROWS" separated by NULL...so scratch everything I've said in this thread... Sometimes you just have to NOT listen to me at all :P Mythran > Mythran, > Brian is referring to a Null Char (ChrW(0)). [quoted text clipped - 101 lines] >>>>>> stream reader to read it line by line? the lines are delimited by >>>>>> CR+LF's thanks! Mythran, > Sometimes you just have to NOT listen to me at all :P I think that can be said about everybody, me included :-)) Especially now that Chris just reminded me that VS.NET itself has trouble showing strings with ChrW(0) in them, which suggests that Brian's Encoding "problem" I suspect is more related to the debugger then to the Encoding object I was suspecting... Jay > Ahh, didn't look at the file...but according to his first post, the > columns are separated by Null. Which I read as "ROWS" separated by [quoted text clipped - 3 lines] > > Mythran <<snip Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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