bytes

[Hacker]

is vb capable of going to cetrain offsets in a file and editing single bytes?

if so wht do i need to know?

[David.Poundall]

Not really. You can load an array of bytes and access them using the array index though. Does that help?

[brucevde]

Sure it can. The following code opens a file, gets the byte at position 87, checks if it is the letter A and if it isn't sets it to the letter A. Check out these I/O functions in your help file - Open, Get, Put, Seek (statement), Seek (function), LOC, LOF, Close

Dim lngFileNo as Long 
Dim bytData as Byte 
 
lngFileNo = FreeFile
 
Open FileName For Binary As lngFileNo
 
Get lngFileNo, 87, bytData
 
If bytData <> Asc("A") then
   Put lngFileNo, 87, asc("A")
End If
 
Close lngFileNo

[Hacker]

ok i need to get to offset 0x3A7E3

and chnage it from 0D to 00

how would i do this?

cuz that way didn't work

[MartinLiss]

Did you try changing the hex value to its decimal equivalent of 239587 and using 13 as the replacement value?

[Hacker]

no i did not...i guess i'll have to find my hex calc

[MartinLiss]

I did the math for you.

[Hacker]

thanks for that...it will help..not sure if this is resolved cuz i havn't tried it...still gotta another project to get done

btw is there an equation for this....or wht...hex calc?

[baja_yu]

Windows calculator can do that

[Hacker]

plz expand on this

[baja_yu]

attached

[brucevde]

There is no conversion necessary, VB will handle everything. In VB, you represent hexadecimal numbers directly by using the prefix &H instead of 0x.

Dim lngFileNo As Long
Dim bytData As Byte
 
lngFileNo = FreeFile
 
Open FileName For Binary As lngFileNo
 
Get lngFileNo, &H3A7E3, bytData
 
If bytData <> &HD Then
   Put lngFileNo, &H3A7E3, &H0
End If
 
Close lngFileNo

[David.Poundall]

Opps - misread the original request. I thought hacker was refering to memory blocks (assembler background kicked in) not files. Apologies for the bum steer.

[David.Poundall]

But actually, I am wrong again. This explains the first steps of even doing that (using StrPtr, VarPtr and ObjPtr). You live and learn.

[Hacker]

alright thats awesome thanks alot to all who helped

[majin]

First off, I am terribly sorry for bringing up a topic thats been buried for 3 years. But I couldn't find any others on my question.
My question is that is there a way to select a region like &H420 to &H430 and check for the things in there and edit it at once? Along the lines of something like:

Dim lngFileNo As Long
      Dim bytData As Byte
      lngFileNo = FreeFile
       Open FileName For Binary As lngFileNo
      Get lngFileNo, &H3A7E3, bytData
      If bytData <> &HD Then
         Put lngFileNo, &H3A7E3, &H0
      End If
             Close lngFileNo

[brucevde]

Get all the bytes in the range and put them into an array.

Dim bytData() as Byte
Redim bytData(&H430 - &H420)
Get lngFileNo, &H3A7E3, bytData
'code to check and change bytData array
'now overwrite the existing data in the file
Put lngFileNo, &H3A7E3, bytData

Just be careful when working with binary files at the byte level. If anything is incorrect the file could become "corrupt"...

[majin]

ah thank you so much for the quick reply
but i have 1 more question, is there a way to put together &H and a variable i want to do &H & var & but it just wont work :S

[MartinLiss]

First off, I am terribly sorry for bringing up a topic thats been buried for 3 years. But I couldn't find any others on my question.
My question is that is there a way to select a region like &H420 to &H430 and check for the things in there and edit it at once? Along the lines of something like:

Dim lngFileNo As Long
      Dim bytData As Byte
      lngFileNo = FreeFile
       Open FileName For Binary As lngFileNo
      Get lngFileNo, &H3A7E3, bytData
      If bytData <> &HD Then
         Put lngFileNo, &H3A7E3, &H0
      End If
             Close lngFileNo

Next time we'd prefer if you started a new thread.