[dba-VB] C# replace a special character

What if the input line wont fit into memory?

max


On 20/10/2009, Stuart McLachlan <stuart at lexacorp.com.pg> wrote:
> 200 megabytes tirivial.
>
> I just knocked this up in PowerBasic (this is the complete program!):
>
> #COMPILE EXE
> #DIM ALL
> FUNCTION PBMAIN () AS LONG
>     LOCAL strFile AS STRING
>     LOCAL lngSTart AS LONG
>     LOCAL strData AS STRING
>     strFile = "ML_Data.mdb"
>     lngStart = TIMER
>     OPEN strFile FOR BINARY AS #1
>     GET$ #1, LOF(1), strData
>     CLOSE #1
>     REPLACE "A" WITH "B" IN strData
>     OPEN strfile & "fixed" FOR BINARY as#1
>     PUT$ #1, strData
>     CLOSE #1
>     MSGBOX "It took " & STR$(TIMER - lngstart) & " seconds"
> END FUNCTION
>
> It compiles to an 11KB executable with no dependencies.
>
> It took 18 seconds to process ML_Data.mdb which is 774MB in size.  Most of
> that time was
> taken in reading and writing the file to/from memory.
>
>
> --
> Stuart
>
>
> On 20 Oct 2009 at 15:53, jwcolby wrote:
>
>> It is my guess that Regex will be too slow.  This will be a file with
>> about 100 characters average
>> per line, 2 million lines.  Doing this in one big read MIGHT be possible
>> (and I will try) but
>> reading in 200 million bytes all at once could cause issues.
>>
>> John W. Colby
>> www.ColbyConsulting.com
>>
>>
>> Jack and Pat wrote:
>> > John,
>> >
>> > I did a google search to find this link. I'm not a C# person, but
>> > thought
>> > I'd pass this on
>> >
>> > http://dotnetperls.com/regex-replace-1
>> >
>> > -----Original Message-----
>> > From: dba-vb-bounces at databaseadvisors.com
>> > [mailto:dba-vb-bounces at databaseadvisors.com] On Behalf Of jwcolby
>> > Sent: Tuesday, October 20, 2009 11:45 AM
>> > To: VBA
>> > Subject: [dba-VB] C# replace a special character
>> >
>> > I have a file which contains a sprinkling of a special character -
>> > decimal
>> > 26, hex 1A (the SUB
>> > character).  This special character in the CSV file output to Accuzip
>> > causes
>> > Accuzip to hiccup.  In
>> > order to get on with my life I need to pre-process the files to get rid
>> > of
>> > this special character.
>> > Because of the size of these files (hundreds of mbytes) I need to do a
>> > readline / replace /
>> > writeline kind of thing.  I think I need to use the
>> > stringbuilder.replace
>> > but I do not know how to
>> > specify replacing this hex 1A with something else.  The something else
>> > would
>> > ideally be nothing
>> > (empty string) but can be any valid alpha character (A, B etc).
>> >
>> > Can anyone help me with this replace part of the problem.  C# syntax
>> > please.
>> >
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>>
>
>
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