Write byte array to file

Ruby
1

Helo

I have method that read a binary file - maybe a image, and return a byte
array.

I want write the byte array to another file. But I keep writing the
bytes as
text. I want binary.

What need I do?

Rajesh.

2

Rajesh Olafson wrote:

Rajesh.

I’m guessing that you’re on Windows. Open the file with the ‘b’ flag,
i.e. ‘wb’.

3

Rajesh.

I’m guessing that you’re on Windows. Open the file with the ‘b’ flag, i.e.
‘wb’.

Thank you.
no. I use linux ubuntu. shold have said that before.

With my file write I just get text in the file. Not binary.
?

Rajesh.

4

Rajesh Olafson wrote:

Then I don’t understand. What do you mean you “just get text”? If you’re
on Linux or you’ve opened the file with the b flag, then you should get
the data you write w/o conversion.

Maybe it would help if you showed an example of your code.

5

Hello Tim,

I do like

file_name=new_foo.gif

myMethod return a byte array for file_name

my_byte_array = myMethod(‘foo.gif’)

puts my_byte_array.class # => Array

outfile = File.new(‘new_foo.gif’, ‘w’)
outfile.puts(byteArray)
outfile.close

now outfile only had some nonsense text.

file new_foo.gif

ascii text

?

Thank you.

Rajesh.

6 
byteArray.each_byte do | byte |

ooops make this
byteArray.each
of course (too many bytes make me dizzy :wink:

7

File.open( ‘new_foo.gif’, ‘w’ ) do |output|
byteArray.each_byte do | byte |
output.print byte.chr
end
end

HTH
Robert

http://ruby-smalltalk.blogspot.com/

As simple as possible, but not simpler.
Albert Einstein

8

Thank you Robert. it work now.
Rajesh.

On Thu, Jun 12, 2008 at 3:51 AM, Robert D. removed_email_address@domain.invalid

9

Hi all, sorry to reopen this issue, I’m facing something weird trying to
reaseemble a binary stream to file. I tried the same code you are using
here:

File.open(‘E:\UpdatePackage\Materials\coco2.jpg’, ‘w’ ) do |output|
a.each do | byte |
output.print byte.chr
end
end

print File.size(‘E:\UpdatePackage\Materials\coco2.jpg’), “\n” # out
1190386
print a.length, “\n” # out 1185939

which is supposed to work fine, BUT the reaasembled file is not valid
and is not the same length in bytes than the array length:

array ‘a’ length: 1185939
new file length: 1190386

For me, this is weird b/c i’m passing exactly all those 1185939 bytes to
file, but the new file is 1190386.

Any idea?
Thanks in advance

Rajesh Olafson wrote:

Thank you Robert. it work now.
Rajesh.

On Thu, Jun 12, 2008 at 3:51 AM, Robert D. removed_email_address@domain.invalid

10

Alexis Alulema wrote:

File.open(‘E:\UpdatePackage\Materials\coco2.jpg’, ‘w’ ) do |output|
a.each do | byte |
output.print byte.chr
end
end

Open the file with “wb”’.

11

Cool, that was great and it finally worked. Thank u very much.

Tim H. wrote:

Alexis Alulema wrote:

File.open(‘E:\UpdatePackage\Materials\coco2.jpg’, ‘w’ ) do |output|
a.each do | byte |
output.print byte.chr
end
end

Open the file with “wb”’.

12

On Dec 22, 2010, at 14:18 , Aegorov E. wrote:

i’m get error
undefined method `chr’ for “255”:String (NoMethodError)
with this code

File.open( filename, ‘wb’ ) do |output|
new_array.each do | byte |
output.print byte.chr
end
end

you have an array of strings of numbers:

[ “255” ].each do |not_a_byte|
…
end

13

i’m get error
undefined method `chr’ for “255”:String (NoMethodError)
with this code

File.open( filename, ‘wb’ ) do |output|
new_array.each do | byte |
output.print byte.chr
end
end

14

On Dec 22, 2010, at 14:40 , Aegorov E. wrote:

i get error
in `chr’: 337 out of char range (RangeError)

337 isn’t a valid 8-bit byte. aka 337 > 255.

What are you actually trying to do? You have too many 1’s for me to
guess.

15

I realized my mistake
i’m write small bmp files аrchiver.
Thank you, Ryan D. .