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Visual Basic 2008 Essentials If you are new to Visual Basic programming with version 2008, this is the place to start your questions.
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Old February 17th, 2008, 05:50 PM
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Default A complex file parser

I need help building a program in VB 2008. Basically, I want to point it at a Binary file, and then have it take the binary, and do the following with it:

1. Take a pair of bits from the beginning of the file
2. Consider the bits, and do the following:
--If they are 00 or 11, toss both of them from the file.
--If the are 01 or 10, keep the first bit, and toss the second one from the file.
3. Move on to the next 2 bits. Repeat.

It needs to do this to the entire file. I plan to simply type in the file location (Like c:\documents and settings\my user name\my documents\randump\dump1.bin) into a text box. It is named "find". The parse will be started by a button named "parse".

There are just possible problems:
1. There is a big chance that the amount of bits removed won't be divisible by 8. This will create an uneven byte at the end. Does the computer care, or should I be worried?
2. When the binary files are opened in notepad, they look like characters. The program needs to see the bits, not characters.

I'm a VB noob, so can somebody show me how one is to do this?

And if you need any more information about the form setup, please ask.

Thanks in advance,

Vistro

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Old February 17th, 2008, 05:54 PM
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BTW, I am not in any classes. This is, therefor, not homework. Everything I know about VB I learned from trial and error... and a book that came with the software.

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Old February 19th, 2008, 01:50 PM
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Files are not organized in bits, but in bytes.  The smallest unit you can retrieve from a file, or put into a file, is a byte.

With that said, prehaps the thing to do—if you are absolutely wedded to this bit-centric approach—is to open an input file and a separate output file. Get a byte from the input file, start parsing til you reach the end of the byte.  While parsing, concatenate, or build, your results using a variable.  When you have a full 8 bits in your variable, write the byte to your output file.  If your tallying takes you across a byte boundary, fill in the last bit of the byte, write it, and continue with this tally event by filling in the 1st bit of the next byte.

Odd task;  why do you want to do this, out of curiosity.
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