Hello,
I have to read a large attachment (7mb) received from email pop3 server.
I am using GET statement, but it needs a buffer to be prepared:
dim buffer as string * 2000
Get #1, , buffer
As we know, the string buffer allocation is limited in VB , and I need it to be extra large
Is there a way to read large binary files in VB?
Thanks
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technically you do not have to know the beginning from the end.
The algorithim just takes the high order 6 bits of each byte, and for files less then three bytes it pads it.
You can read a buffer of what ever size you want, and chunk it yourself without any issues, The 1kb thing is just a suggestion.
ABCD is 32 bits long or 8 bits * 4 bytes = 32 bits
base 64 takes the first 6 high order bytes, so you must have a multple of 6 bits, so padding is added so that when the process is reversed it returns to the exact same size.
Padding occurs so that each multiple is an even 3
A B C D PADDING PADDING
01000001 01000010 01000011 01000100 00000000 00000000
Q U J D R A = =
010000 010100 001001 000011 010001 000000 000000 000000
To decode just read each line and take 4 bytes at a time and decode to be 3 binary bytes and append to your file, or chunk it by 1024 buffer size should be 768 bytes of binary data.
intFilenum = Freefile
Open strEmailAttachmentFilename
ReDim bytBuffer(0 To LOF(intFilenum) - 1)
Get intFilenum, 1, bytBuffer
Close intFilenum
====================
Note: it is advisable to use the Freefile statement to return an unused file handle rather than hard-coding a file handle (as you have done)
school1282,
Thank you for the points. The grade with which you closed this discussion thread indicates you still have a problem that we didn't properly address. Is reading a large binary file still a problem? The code snippet I supplied should read the entire file with one operation. It should be VERY fast compared to multiple (chunk) reads.
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by: BrianGEFF719Posted on 2004-12-14 at 04:54:36ID: 12818664
Why dont you save to disk in blocks of 1024 bytes, and then base 64 decode 1kb at a time?
-Brian