DEV Community

Super Kai (Kazuya Ito)
Super Kai (Kazuya Ito)

Posted on • Edited on

Bytearray in Python (6)

#python #bytestring #bytes #bytearray

Buy Me a Coffee☕

*Memo:

bytearray() can create a bytearray with or without several types of objects or can encode a string to a bytearray as shown below:

*Memo to create a bytearray:

  • The 1st argument is source(Optional-Default:b''-Type:Bytes-like object/Iterable(int)/int):
    • int gives a null value(\x00) which represents no value.

*Memo to encode a string to a bytearray:

  • The 1st argument is source(Required-Type:str).
  • The 2nd argument is encoding(Required-Type:str):
    • 'utf-8', 'utf-7', 'utf-16', 'big5', 'ascii', etc can be set to it.
    • You can see Standard Encodings for more possible values.
  • The 3rd argument is errors(Optional-Default:'strict'-Type:str):
    • It controls encoding error with the error handlers, 'strict', 'ignore', 'replace', 'xmlcharrefreplace', 'backslashreplace', etc.
    • 'strict' raises UnicodeError if the character and byte, which cannot be encoded and decoded, exists respectively.
    • 'ignore' ignores the character and byte which cannot be encoded and decoded respectively.
    • 'replace' replaces the character and byte, which cannot be encoded and decoded, with ? for encoding and � for decoding respectively.
    • 'xmlcharrefreplace' replaces the character, which cannot be encoded, with the XML/HTML numeric character reference format &#num;:
      • It doesn't support decoding so error occurs for the byte which cannot be decoded while error doesn't occur for the byte which can be decoded.
    • 'backslashreplace' replaces the character and byte, which cannot be encoded and decoded, with the hexadecimal format \xhh, \uxxxx or \Uxxxxxxxx for encoding and \xhh for decoding respectively.
    • You can see more error handlers.
    • You can create your own error handler with codecs.register_error().

<Create a bytearray>: 

v = bytearray()                            # Empty bytearray
v = bytearray(b'')                         # Empty bytearray
v = bytearray(source=b'12')                # bytes
v = bytearray(source=bytearray(b'12'))     # bytearray
v = bytearray(source=12)                   # int
v = bytearray(source=True)                 # bool
v = bytearray(source=[1, 2, 3])            # list(int)
v = bytearray(source=(1, 2, 3))            # tuple(int)
v = bytearray(source={1, 2, 3})            # set(int)
v = bytearray(source=frozenset({1, 2, 3})) # frozenset(int)
v = bytearray(source={1:2, 3:4})           # dict(int:int)
v = bytearray(source={1:2, 3:4}.keys())    # dict(int:int).keys()
v = bytearray(source={1:2, 3:4}.values())  # dict(any:int).values() 
v = bytearray(source=iter([1, 2, 3]))      # iterator(int)
v = bytearray(source=range(10, 20))        # range
# No error

print(type(bytearray()))
# <class 'bytes'>

v = bytearray(source='12')               # str
v = bytearray(source=1.2)                # float
v = bytearray(source=1.2+3.4j)           # complex
v = bytearray(source={1:2, 3:4}.items()) # dict(int:int).items()
v = bytearray(source=lambda: 10)         # function
# Error
Enter fullscreen mode Exit fullscreen mode 
# Empty bytearray
v = bytearray()
v = bytearray(b'')

print(v)
# bytearray(b'')
Enter fullscreen mode Exit fullscreen mode 
v = bytearray(source=b'12')            # bytes
v = bytearray(source=bytearray(b'12')) # bytearray

print(v, v[0], v[1])
# bytearray(b'12') 49 50
Enter fullscreen mode Exit fullscreen mode 
v = bytearray(source=12) # int

print(v, v[0], v[1], v[2], v[3], v[4])
# bytearray(b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00') 0 0 0 0 0
Enter fullscreen mode Exit fullscreen mode 
v = bytearray(source=True) # bool

print(v, v[0])
# bytearray(b'\x00') 0
Enter fullscreen mode Exit fullscreen mode 
v = bytearray(source=[1, 2, 3]) # list

print(v, v[0], v[1], v[2])
# bytearray(b'\x01\x02\x03') 1 2 3
Enter fullscreen mode Exit fullscreen mode 
v = bytearray(source=(1, 2, 3)) # tuple

print(v, v[0], v[1], v[2])
# bytearray(b'\x01\x02\x03') 1 2 3
Enter fullscreen mode Exit fullscreen mode 
v = bytearray(source={1, 2, 3})            # set(int)
v = bytearray(source=frozenset({1, 2, 3})) # frozenset(int)

print(v, v[0], v[1], v[2])
# bytearray(b'\x01\x02\x03') 1 2 3
Enter fullscreen mode Exit fullscreen mode 
v = bytearray(source={1:2, 3:4})        # dict(int:int)
v = bytearray(source={1:2, 3:4}.keys()) # dict(int:int).keys()

print(v, v[0], v[1])
# bytearray(b'\x01\x03') 1 3
Enter fullscreen mode Exit fullscreen mode 
v = bytearray(source={1:2, 3:4}.values()) # dict(int:int).values() 

print(v, v[0], v[1])
# bytearray(b'\x02\x04') 2 4
Enter fullscreen mode Exit fullscreen mode 
v = bytearray(source=iter([1, 2, 3])) # iterator(int)

print(v, v[0], v[1], v[2])
# bytearray(b'\x01\x02\x03') 1 2 3
Enter fullscreen mode Exit fullscreen mode 
v = bytearray(source=range(10, 20)) # range

print(v, v[0], v[1], v[2], v[3], v[4], v[5], v[6])
# bytearray(b'\n\x0b\x0c\r\x0e\x0f\x10\x11\x12\x13') 10 11 12 13 14 15 16
Enter fullscreen mode Exit fullscreen mode

<Encode a string to a bytearray>: 

v = "Lёт's gφ!" # Let's go!

print(bytearray(source=v, encoding='utf-8'))
print(bytearray(source=v, encoding='utf-8', errors='strict'))
# bytearray(b"L\xd1\x91\xd1\x82\'s g\xcf\x86!")
Enter fullscreen mode Exit fullscreen mode 
v = "Lёт's gφ!" # Let's go!

print(bytearray(source=v, encoding='utf-7'))
# bytearray(b"L+BFEEQg\'s g+A8Y!")
Enter fullscreen mode Exit fullscreen mode 
v = "Lёт's gφ!" # Let's go!

print(bytearray(source=v, encoding='utf-16'))
# bytearray(b"\xff\xfeL\x00Q\x04B\x04\'\x00s\x00 \x00g\x00\xc6\x03!\x00")
Enter fullscreen mode Exit fullscreen mode 
v = "Lёт's gφ!" # Let's go!

print(bytearray(source=v, encoding='big5'))
# bytearray(b"L\xc7\xce\xc7\xdb\'s g\xa3p!")
Enter fullscreen mode Exit fullscreen mode 
import codecs

def hashreplace_handler(x):
    return ((x.end - x.start) * '#', x.end)

codecs.register_error('hashreplace', hashreplace_handler)

v = "Lёт's gφ!" # Let's go!

print(bytearray(source=v, encoding='ascii', errors='ignore'))
# bytearray(b"L\'s g!")

print(bytearray(source=v, encoding='ascii', errors='replace'))
# bytearray(b"L??\'s g?!")

print(bytearray(source=v, encoding='ascii', errors='xmlcharrefreplace'))
# bytearray(b"L&#1105;&#1090;\'s g&#966;!")

print(bytearray(source=v, encoding='ascii', errors='backslashreplace'))
# bytearray(b"L\\u0451\\u0442\'s g\\u03c6!")

print(bytearray(source=v, encoding='ascii', errors='hashreplace'))
# bytearray(b"L##\'s g#!")

print(bytearray(source=v, encoding='ascii', errors='strict'))
# UnicodeEncodeError: 'ascii' codec can't encode characters
# in position 1-2: ordinal not in range(128)
Enter fullscreen mode Exit fullscreen mode

Top comments (0)