How to create a bytes or bytearray of given length filled with zeros in Python?

Question

All the solutions I found were for lists.

Thanks.

Asked By: Yan

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Answer 1

This will give you 100 zero bytes:

bytearray(100)

Or filling the array with non zero values:

bytearray([1] * 100)

Answered By: Ned Batchelder

Answer 2

For bytes, one may also use the literal form b'' * 100.

# Python 3.6.4 (64-bit), Windows 10
from timeit import timeit
print(timeit(r'b"" * 100'))  # 0.04987576772443264
print(timeit('bytes(100)'))  # 0.1353608166305015

Update1: With constant folding in Python 3.7, the literal from is now almost 20 times faster.

Update2:
Apparently constant folding has a limit:

>>> from dis import dis
>>> dis(r'b"" * 4096')
  1           0 LOAD_CONST               0 (b'x00x00x00...')
              2 RETURN_VALUE
>>> dis(r'b"" * 4097')
  1           0 LOAD_CONST               0 (b'x00')
              2 LOAD_CONST               1 (4097)
              4 BINARY_MULTIPLY
              6 RETURN_VALUE

Answered By: AXO

How to create a bytes or bytearray of given length filled with zeros in Python?

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