CODEWITHSUNDEEP
ruby
AllanNorgaard
AllanNorgaard

Reputation: 284

Packing a string to contain null-bytes

I want to pack a string containing "00000000".

If i do "00000000".to_a.pack('H*') I get an error

in 'system': string contains null byte (ArgumentError)

I need to send this as a hex string to a microprocessor. A sample could be 0x81 0x00 0x00 0x21

Upvotes: 2

Views: 2334

Answers (2)

Theo
Theo

Reputation: 132902

Try this:

input = "A000B0"
output = []
until input.empty?
  output << input[0, 2].to_i(16)
  input = input[2..-1]
end
puts output.pack('C*').inspect # => "\xA0\x00\xB0"

Upvotes: 1

Michael Kohl
Michael Kohl

Reputation: 66837

There's a pack directive for null bytes: x.

>> ["a", "b"].pack("HxH") #=> "\xA0\x00\xB0"

Upvotes: 3

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