Python bytearray() Function

The Python bytearray() function returns a new array of bytes which is a mutable sequence of integers in the range 0 <= x < 256.

python bytearray() function

What is bytearray?

A bytearray is very similar to a regular python string (str in python2.x, bytes in python3). There is an important difference though, that is strings are immutable, whereas bytearrays are mutable (like a list of characters).

The Python bytearray() function returns bytearray object which is a mutable sequence of integers in the range 0 <= x < 256. Hence, bytearray() function allows one to manipulate its elements as the numbers in the 0-256 range or one-char strings.

Python bytearray() Syntax

bytearray([source[, encoding[, errors]]])

The bytearray() method takes three optional parameters.

1: First parameter is Source (optional)

Source is an optional parameter that can be used to initialize the array in a few different ways:

  • If the source is a string, encoding is required. You must also give the encoding (and optionally, errors) parameters; bytearray() then converts the string to bytes using str.encode().
  • If the source is an integer, the array will have that size and will be initialized with null bytes.
  • If the source is an object conforming to the buffer interface, a read-only buffer of the object will be used to initialize the bytes array.
  • If the source is an iterable, it must be an iterable of integers in the range 0 <= x < 256, which are used as the initial contents of the array.
  • Without an argument, the bytearray() method will create an array of size 0.

2: Second parameter is Encoding (optional)

Encoding is also optional. However, it is required if the source is a string. Examle: utf-8, ascii etc.

3: Third parameter is Error (optional)

It is also an optional parameter. Depending on different conditions, it can have values like strict, replace, ignore etc.

Python bytearray() Example

>>> bytearray()  #without argument
bytearray(b' ')
>>> bytearray(3)  #array of bytes of given integer
>>> bytearray([1,2,3])  #bytearray() in iterable list
>>> bytearray('Python','utf-8')  #bytearray() and string
>>> bytearray('Python', 'ascii')

Python bytearray() throws following error when we use non-ASCII characters without any encoding and specifying the error.

>>> bytearray('źebra')  #without encoding
Traceback (most recent call last):
TypeError: string argument without an encoding

>>> bytearray('źebra','ascii') #encoding without specifying error
Traceback (most recent call last):
UnicodeEncodeError: 'ascii' codec can't encode 
character '\u017a' in position 0: ordinal not in range(128)

>>> bytearray('źebra','ascii','ignore')  #specifying error
bytearray(b'ebra')   #ignores the non-ASCII character

>>> bytearray('źebra','ascii','replace')  #using error replace

That is all about Python bytearray(). You have learned about bytearray() with relevant examples.