Robert Klemme
6/18/2007 6:52:00 AM
On 18.06.2007 03:52, Melissa Silas wrote:
> Hey, I'm looking for some help with reading / writing binary string.
> Just need some help understanding what exactly is going on..
>
> if I have a string like:
> str = "\t\005\001\006\afoo\006\abar"
>
> Or if I have something like:
> str =
> "\t\025\001\004\001\004\002\004\003\004\004\004\005\004\006\004\a\004\b\004\t\004\n"
>
> What exactly kind of format is that?
Um, how can we know what format this is? I mean, you came up with that
string. The definition above just uses octal escapes. You can as well
have hex codes:
irb(main):013:0> "\x21\x20\x40"
=> "! @"
> How do I parse it / read binary
> data from it?
Depends on what you want to do with it. If you want to access bytes you
can simply do this
irb(main):014:0> s = "\t\001"
=> "\t\001"
irb(main):015:0> s[0]
=> 9
irb(main):016:0> s[1]
=> 1
If you want bits you can do
irb(main):017:0> s.unpack "b*"
=> ["1001000010000000"]
irb(main):018:0> s.unpack "b8b8"
=> ["10010000", "10000000"]
irb(main):019:0> s.unpack "b4*"
=> ["1001"]
irb(main):020:0> s.unpack "b4b4b4b4"
=> ["1001", "1000", "", ""]
irb(main):021:0> s.unpack "b4b4b"
=> ["1001", "1000", ""]
irb(main):022:0> s.unpack "b4b4"
=> ["1001", "1000"]
Please see #unpack docs for more info.
> And how can I write the same type of string from say an
> array? ["foo","bar"]?
"Write from an array"? I don't understand what you mean. If you want to
put it into an array, you can simply do
irb(main):023:0> ["foo", "\tbar\n"]
=> ["foo", "\tbar\n"]
Kind regards
robert