Search through a (large) binary file.
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From: Michelle on 10 Sep 2009 10:43 I need some help to search through a (sometimes large) binary file. I'd like to search within this binary file for a pattern containing a particular hex value (e.g. FF56131A1B087B15610800151E). When the pattern is found, i need to know the (start) offset, because then I'd like to read the 4 previous bytes (need the hex values). I suppose that i need to read the file in blocks (500 kb or 1 mb) because it's a large file. I 'am a rookie using C#, so if possible please share a piece of code. Thanks in advance, Michelle
From: Fred Mellender on 10 Sep 2009 11:03 "read binary file c#" in Google returns many hits, including: http://www.codersource.net/csharp_read_write_binary_files.html http://www.yoda.arachsys.com/csharp/readbinary.html http://dotnetperls.com/binaryreader "Michelle" <michelle(a)notvalid.nomail> wrote in message news:OSzELUiMKHA.3672(a)TK2MSFTNGP02.phx.gbl... >I need some help to search through a (sometimes large) binary file. > > I'd like to search within this binary file for a pattern containing a > particular hex value (e.g. FF56131A1B087B15610800151E). > When the pattern is found, i need to know the (start) offset, because then > I'd like to read the 4 previous bytes (need the hex values). > I suppose that i need to read the file in blocks (500 kb or 1 mb) because > it's a large file. > > I 'am a rookie using C#, so if possible please share a piece of code. > > Thanks in advance, > > Michelle >
From: Jeff Johnson on 10 Sep 2009 12:19 "Michelle" <michelle(a)notvalid.nomail> wrote in message news:OSzELUiMKHA.3672(a)TK2MSFTNGP02.phx.gbl... >I need some help to search through a (sometimes large) binary file. > > I'd like to search within this binary file for a pattern containing a > particular hex value (e.g. FF56131A1B087B15610800151E). > When the pattern is found, i need to know the (start) offset, because then > I'd like to read the 4 previous bytes (need the hex values). > I suppose that i need to read the file in blocks (500 kb or 1 mb) because > it's a large file. Define "large," because you'd be better of if you can read the entire thing into a byte array and then just work off that byte array. Using chunks forces you to deal with the situation where the data you're searching for is split across the end of one chunk and the beginning of the next.
From: Michelle on 10 Sep 2009 12:36 It's not only reading a binary file, but also searching for a particular hex value (pattern). And what about if my pattern is at the block border ? "Fred Mellender" <nospam_fredm73(a)gmail.com> wrote in message news:%23Fov8fiMKHA.5072(a)TK2MSFTNGP05.phx.gbl... > "read binary file c#" in Google returns many hits, including: > http://www.codersource.net/csharp_read_write_binary_files.html > http://www.yoda.arachsys.com/csharp/readbinary.html > http://dotnetperls.com/binaryreader > > > > "Michelle" <michelle(a)notvalid.nomail> wrote in message > news:OSzELUiMKHA.3672(a)TK2MSFTNGP02.phx.gbl... >>I need some help to search through a (sometimes large) binary file. >> >> I'd like to search within this binary file for a pattern containing a >> particular hex value (e.g. FF56131A1B087B15610800151E). >> When the pattern is found, i need to know the (start) offset, because >> then I'd like to read the 4 previous bytes (need the hex values). >> I suppose that i need to read the file in blocks (500 kb or 1 mb) because >> it's a large file. >> >> I 'am a rookie using C#, so if possible please share a piece of code. >> >> Thanks in advance, >> >> Michelle >> >
From: Michelle on 10 Sep 2009 12:37
Mostly more then 1 Gb. "Jeff Johnson" <i.get(a)enough.spam> wrote in message news:%23BEECKjMKHA.3672(a)TK2MSFTNGP02.phx.gbl... > "Michelle" <michelle(a)notvalid.nomail> wrote in message > news:OSzELUiMKHA.3672(a)TK2MSFTNGP02.phx.gbl... > >>I need some help to search through a (sometimes large) binary file. >> >> I'd like to search within this binary file for a pattern containing a >> particular hex value (e.g. FF56131A1B087B15610800151E). >> When the pattern is found, i need to know the (start) offset, because >> then I'd like to read the 4 previous bytes (need the hex values). >> I suppose that i need to read the file in blocks (500 kb or 1 mb) because >> it's a large file. > > Define "large," because you'd be better of if you can read the entire > thing into a byte array and then just work off that byte array. Using > chunks forces you to deal with the situation where the data you're > searching for is split across the end of one chunk and the beginning of > the next. > |