# Writing 8-bit bytes
**URL:** https://discourse.julialang.org/t/writing-8-bit-bytes/15334
**Category:** General Usage
**Created:** [September 22, 2018, 10:57am UTC](https://discourse.julialang.org/t/writing-8-bit-bytes/15334 "2018-09-22T10:57:53Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@David\_Feldman](https://discourse.julialang.org/u/David_Feldman)
#### Post date: [September 22, 2018, 10:57am UTC](https://discourse.julialang.org/t/writing-8-bit-bytes/15334/1 "2018-09-22T10:57:53Z")
I wanted to create a certain file consisting of 8-bit bytes (to conform with a picture format).
In the following, the value of Q was always in the range 0-255. But the command
write(OUT, convert(UInt8,floor(Q)))
actually wrote zero-padded 16-bit bytes to the file OUT. Thus output file came out twice the size I expected. Indeed, using another programming language, I got the desired result by “dealing” 8-bit bytes (like card) between to two files (the other of which got filled with 0’s and thus subsequently discarded).
How can I write 8-bit bytes in Julia? I’m using Windows 10 on a 64-bit machine, if that makes a difference.
Thank you.
---
### Author:  [@stevengj](https://discourse.julialang.org/u/stevengj)
#### Post date: [September 22, 2018, 12:15pm UTC](https://discourse.julialang.org/t/writing-8-bit-bytes/15334/2 "2018-09-22T12:15:12Z")
It works fine for me. For example:
```julia
julia> a = rand(1024);
julia> open("tst.dat", "w") do f
for x in a
write(f, convert(UInt8, floor(x)))
end
end
julia> filesize("tst.dat")
1024
```
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### Author:  [@David\_Feldman](https://discourse.julialang.org/u/David_Feldman)
#### Post date: [September 22, 2018, 7:16pm UTC](https://discourse.julialang.org/t/writing-8-bit-bytes/15334/3 "2018-09-22T19:16:26Z")
Either “weird.”
Or…perhaps filesize is counting 16-bit blocks?
That would be consistent. I’ll try filesize with my code and see what it reports.
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### Author:  [@stevengj](https://discourse.julialang.org/u/stevengj)
#### Post date: [September 22, 2018, 7:18pm UTC](https://discourse.julialang.org/t/writing-8-bit-bytes/15334/4 "2018-09-22T19:18:04Z")
filesize returns the size in bytes (8 bits).
Probably you have some mistake, but it is hard to tell what is going on if you don’t provide a self-contained example like what I posted.
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### Author:  [@David\_Feldman](https://discourse.julialang.org/u/David_Feldman)
#### Post date: [September 22, 2018, 7:53pm UTC](https://discourse.julialang.org/t/writing-8-bit-bytes/15334/5 "2018-09-22T19:53:16Z")
Agreed.
I can reproduce your example. I’ll look for my mistake now.
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### Author:  [@David\_Feldman](https://discourse.julialang.org/u/David_Feldman)
#### Post date: [September 22, 2018, 7:55pm UTC](https://discourse.julialang.org/t/writing-8-bit-bytes/15334/6 "2018-09-22T19:55:54Z")
Found it. Thanks… Probably this topic should be deleted.
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### Author:  [@StefanKarpinski](https://discourse.julialang.org/u/StefanKarpinski)
#### Post date: [September 22, 2018, 8:07pm UTC](https://discourse.julialang.org/t/writing-8-bit-bytes/15334/7 "2018-09-22T20:07:33Z")