An old question: how do I output a vector of UInt8 in binary?

New to Julia
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So far, I am writing the bytes individually. That seems inefficient. Are there better alternatives, perhaps converting the vector to a byte string?

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Output to where? A vector of UInt8 is a byte string

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A vector of UInt8 is already in memory as binary. Julia displays it to humans in hexadecimal representation by default. Pretty much any way you look at it, you’ll just see a vector of UInt8. Do you want to write those bytes to a file? That’s a write:

julia> write("file.bin", [0x68, 0x65, 0x6c, 0x6c, 0x6f, 0x0a])
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shell> xxd file.bin
00000000: 6865 6c6c 6f0a                           hello.

Do you want to see the literal ones and zeros? Julia can show those to you as a string of '0's and '1's with bitstring:

julia> bitstring.([0x68, 0x65, 0x6c, 0x6c, 0x6f, 0x0a])
6-element Vector{String}:
 "01101000"
 "01100101"
 "01101100"
 "01101100"
 "01101111"
 "00001010"

Or you can even print it out as the Julia syntax to reconstruct the very same vector, using binary integer literals with the 0b syntax of 0s and 1s:

julia> println("[", join(string.("0b", bitstring.([0x68, 0x65, 0x6c, 0x6c, 0x6f, 0x0a])), ", "), "]")
[0b01101000, 0b01100101, 0b01101100, 0b01101100, 0b01101111, 0b00001010]

julia> show([0b01101000, 0b01100101, 0b01101100, 0b01101100, 0b01101111, 0b00001010])
UInt8[0x68, 0x65, 0x6c, 0x6c, 0x6f, 0x0a]

These are all just different ways of interpreting (or displaying) the same bit pattern. The bit pattern 01101000 can be interpreted as hexadecimal (0x68) or decimal (104) or even the ASCII 'h'… or anything, really.

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Ok, thanks. I don’t understand why I’m having problems, then. I’ll go back over my code.