Re: [Rails] ruby pack unexpected results
On 24 June 2013 20:59, Colin Law wrote:
> On 24 June 2013 17:49, John Merlino wrote:
>> I have two hex values and expect back the value "3007"
>>
>>
>> What pack does is take the array of hexes and formats them into a string (if
>> ASCII representation, then ASCII character, otherwise the raw hex as
>> string). Then I take the string of hexes and unpack them, that is, get the
>> unsigned int representation of those bytes:
>> [0xBF, 0xB].pack('C*').unpack('I')[0]
>>
>> So I expect back 3007, but the above produces nil.
>
> Do the operation one step at a time in irb and you will see where it goes
> wrong.
Hint: unpack('I') appears to expect four bytes.
Colin
>
> Colin
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Re: [Rails] ruby pack unexpected results
On 24 June 2013 17:49, John Merlino wrote:
> I have two hex values and expect back the value "3007"
>
>
> What pack does is take the array of hexes and formats them into a string (if
> ASCII representation, then ASCII character, otherwise the raw hex as
> string). Then I take the string of hexes and unpack them, that is, get the
> unsigned int representation of those bytes:
> [0xBF, 0xB].pack('C*').unpack('I')[0]
>
> So I expect back 3007, but the above produces nil.
Do the operation one step at a time in irb and you will see where it goes wrong.
Colin
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[Rails] ruby pack unexpected results
I have two hex values and expect back the value "3007"
What pack does is take the array of hexes and formats them into a string
(if ASCII representation, then ASCII character, otherwise the raw hex as
string). Then I take the string of hexes and unpack them, that is, get the
unsigned int representation of those bytes:
[0xBF, 0xB].pack('C*').unpack('I')[0]
So I expect back 3007, but the above produces nil.
This is what I want to achieve:
[0xBF, 0xB].reverse.inject { |s,v| s * 256 + v }
=> 3007
But I want to use unpack instead of inject.
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