Need help on #pack and #unpack

ruby-talk
1

a = ['2015',"This is", "one value","test",'9820']
string = a.pack('Z*A*Z*Z*Z*') # => "2015\x00This isone
value\x00test\x009820\x00"
string.unpack('Z*Z*Z*Z*') # => ["2015", "This isone value", "test",
"9820"]

But I want as

["2015", "This is one value", "test", "9820"]

How to do this ?

···

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2

Add a space character to your inputs. AFAIK #pack and #unpack can't do that
for you. They're not exactly string manipulation functions after all,
they're data de/serialisers.

···

On Mar 11, 2014 4:18 AM, "Arup Rakshit" <lists@ruby-forum.com> wrote:

a = ['2015',"This is", "one value","test",'9820']
string = a.pack('Z*A*Z*Z*Z*') # => "2015\x00This isone
value\x00test\x009820\x00"
string.unpack('Z*Z*Z*Z*') # => ["2015", "This isone value", "test",
"9820"]

But I want as

["2015", "This is one value", "test", "9820"]

How to do this ?

--
Posted via http://www.ruby-forum.com/.

3

Matthew Kerwin wrote in post #1139417:

Thank you very much. Could you tell me what do you mean by below ?
Probably one small use-case from your experience.

···

for you. They're not exactly string manipulation functions after all,
they're data de/serialisers.

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4

Arup Rakshit wrote in post #1139420:

Matthew Kerwin wrote in post #1139417:

Thank you very much. Could you tell me what do you mean by below ?
Probably one small use-case from your experience.

for you. They're not exactly string manipulation functions after all,
they're data de/serialisers.

Well, for example, imagine you're saving some image data as a TGA file.
You could do something like this:

  COLOUR_MAP_NONE = 0
  IMAGE_TYPE_RGB = 2

  tga_header = [
    0,
    COLOUR_MAP_NONE,
    IMAGE_TYPE_RGB,
    0, 0, 32, # palette
    0, 0, # x, y origin of pixels
    255, 255, # width, height of image
    24, # bits per pixel
    0,
  ].pack 'CCCSSCSSSSCC'

... and similarly, if you're loading it:

  identsz, cm_type, image_type,
    cm_start, cm_length, cm_bits,
    xstart, ystart, width, height, bits, descriptor =
      tga_header.unpack 'CCCSSCSSSSCC'

data packets over a network (e.g. HTTP/2 is a binary format).

···

From my personal experience, I've mostly used pack/unpack for sending

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