I have a simple byte array
["\x01\x01\x04\x00"]
I'm not sure how I can alter just the second value in the string (I know the array only has one item), whilst still keeping the object a byte array.
Something along these lines:
["\x01#{ARGV[0]}\x04\x00"]
I think the secret is that you have a nested array:
irb(main):002:0> x = ["\x01\x02\x01\x01"]
=> ["\001\002\001\001"]
You can index it:
irb(main):003:0> x[0][1]
=> 2
You can assign into it:
irb(main):004:0> x[0][1] = "\x05"
=> "\005"
And it looks like what you want:
irb(main):005:0> x
=> ["\001\005\001\001"]
use each_byte string method:
$ irb --simple-prompt
>> str = "\x01\x01\x04\x00"
=> "\001\001\004\000"
>> str.each_byte {|byte| puts byte}
1
1
4
0
=> "\001\001\004\000"
>>
It might be less confusing to get rid of the array wrapper.
a = ["\x01\x01\x04\x00"]
a = a[0]
a[1] = ...
You can always put the string back inside an array:
a = [a]
Also, technically, it's not a "byte array", it's a single-element Array, with a String object. (And for that matter, strictly speaking, Ruby doesn't really have Array of Type; all Ruby arrays are something like Array of Object elsewhere.)
