3

The answers to this question make it seem like there are two ways to convert an integer to a bytes object in Python 3. They show

s = str(n).encode()

and

n = 5    
bytes( [n] )

Being the same. However, testing that shows the values returned are different: 

print(str(8).encode()) 
#Prints b'8'

but

print(bytes([8])) #prints b'\x08'

I know that the first method changes the int 8 into a string (utf-8 I believe) which has the hex value of 56, but what does the second one print? Is that just the hex value of 8? (a utf-8 value of backspace?)

Similarly, are both of these one byte in size? It seems like the second one has two characters == two bytes but I could be wrong there...

Community
  • 1
  • 1
Startec
  • 12,496
  • 23
  • 93
  • 160
  • the \x in \x08 is just indicating that the 08 is a hex number. Both results are one byte. – Clarus Aug 26 '14 at 00:01
  • 1
    How do the answers show them being the same? The answers make it very clear that they're doing different things—one returns the ASCII-encoded string representation of the number 8, the other returns the byte 8. These are not at all the same. – abarnert Aug 26 '14 at 00:03
  • 1
    Also, if you want to know how long the second one is, why not ask it: `print(len(bytes([8])))` will give you `1`. It is just the single UTF-8 value of backspace, as you suspected, which is one byte, not two. – abarnert Aug 26 '14 at 00:06

2 Answers2

5

b'8' is a bytes object which contains a single byte with value of the character '8' which is equal to 56.

b'\x08' is a bytes object which contains a single byte with value 8, which is the same as 0x8.

Anton Savin
  • 40,838
  • 8
  • 54
  • 90
3

Those two examples are not equivalent. str(n).encode() takes whatever you give it, turns it into its string representation, and then encodes using a character codec like utf8. bytes([..]) will form a bytestring with the byte values of the array given. The representation \xFF is in fact the hexadecimal representation of a single byte value.

>>> str(8).encode()
b'8'
>>> b'8' == b'\x38'
True
Te-jé Rodgers
  • 878
  • 1
  • 7
  • 20
  • When I do str(8) it just returns 8 as a string, not a byte object. When you say "byte values" do you mean their decimal values? – Startec Aug 26 '14 at 01:31
  • 1
    My apologies, I omitted the `.encode` by accident. However, you should note that what that `.encode()` does is take the unicode string and transform it to an 8-bit string (i.e. a bytestring) using a character codec; in the end it still represents text. When I say an array of "byte values", I do mean decimals. Specifically integers in the range [0,255]. Any value greater than 255 or less than 0 would give you an error, because it's not a byte! – Te-jé Rodgers Aug 26 '14 at 02:46