I'm trying to understand what happen when someone try to write to a file the next way:
q)h:hopen `:out
q)h (1 2;3)
3i
q)hclose h
q)read1 `:out
0x07000200000001000000000000000200000000000000f90300000000000000
this is not the same as a binary representation:
q)-8!(1 2;3)
0x010000002d00000000000200000007000200000001000000000000000200000000000000f90300000000000000
(1 2;3) was written into :out?-9!-8!(1 2;3)set/get related to these binary data formats? - do they use another 3-rd different binary data format?Technically you can read the object if you have a little prior knowledge about the object, such that you can fabricate a header:
q)read1`:out
0x07000200000001000000000000000200000000000000f90300000000000000
q)-9!read1`:out
'badmsg
[0] -9!read1`:out
^
q)-9!{0x01,0x000000,(reverse 0x0 vs `int$count[x]+1+3+4+1+1+4),0x00,0x00,(reverse 0x0 vs 2i),x}read1`:out
1 2
3
The header here is comprised of:
0x01 - little endian
0x000000 - filler
message length (count of raw `x` plus the header additions)
0x00 - type (generic list = type 0) ... you have to know this in advance
0x00 - attributes .... none here, you would have to know this
length of list .... here we knew it was a 2-item list
x - the raw bytecode of the object without header
As rianoc pointed out, there are better ways to write such objects such that they can be more easily read without requiring advanced knowledge