Short String/integer compression

Hans Kreiger

Hey,

I need to compress relatively short strings(or integer/long) in vb.net, i've been told base64 is the direction to head in, but simply using convert.tobase64string() on a string of my length just makes it longer

the strings i will be using will always be of the same length and type, just different numbers, for example: "1406891123456777"

any level of compression is appreciated

Thanks,

Howard

6 Replies

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Sam Hobbs16y ago
You say "commport" and I assume that is the same as a serial port. Does the device support 8 bits? For serial communication, the number of bits are usually either 7 or 8 and for binary data you need to use 8 bits. If you use 8 bits, then as far as I know there is no conversion necessary.
Hans Kreiger16y ago
Sorry, yes it can be stored as binary, what you mention there is what i need to be doing

Would you mind expanding on that for a larger string and maybe point me towards some vb.net functions that i should use to achieve it?
Sam Hobbs16y ago
Base64 is used to send binary data, such as images, as text. If the 16 digits are already text then you don't need base64.

Perhaps what your instructor is saying is that you could make the data binary, so that the value 257 would be 0101 hexadecimal (two bytes). If the data is text data, then 257 I think would be 323537 hexadecimal (3 bytes). If you can send the binary data, then it will be shorter than if you send the text. If however you must send text data, then if you convert the binary data using base64, then the data I think would be shorter than if the numbers are sent as text.

So the question "Can the output be binary or does the output need to be text?" is highly relevant and I don't understand "anything really so long as i can convert it to byte array without losing the compress effect", especially since there would be no compression if the data is sent as binary. The compression is not relevant if you send the data as binary, so answerig the question of whether the data can be sent as binary by saying that the data must be sent without losing compression is just making an infinte loop.
Hans Kreiger16y ago
bump
Hans Kreiger16y ago
i need to write the 16 byte string to an RFID tag via commport, i will decompress it when it returns when i read it

my tutor said he successfully achieved this using base 64

Can the output be binary or does the output need to be text?
   the output will need to be a byte array eventually, but anything really so long as i can convert it to byte array without losing the compress effect
Will the numbers occur multiple times within the data to be compressed or just once?
   there will be several sets of 16 digits to compress individually, each will only appear once (they are blood test results), i do not have all the examples to display as i have not finished making them yet, but they are just 16 digit numbers
Is it necessary to also compress the delimiting characters or can delimiting characters be not saved?
   there are no delimiting characters between the numbers, just the 16 digits, without the quotes

Thanks,

Howard
Sam Hobbs16y ago
Yes base64 is the opposite of what you need; anyone that suggests it is not listening to your requirements. Your requirements however are not clear.

Can the output be binary or does the output need to be text?

Will the numbers occur multiple times within the data to be compressed or just once?

Is it necessary to also compress the delimiting characters or can delimiting characters be not saved? When I say delimiting characters, I mean characters between the numbers.