Data buffer allocation

Provides a mutable sequence of bytes for low-level binary manipulation.

File processing: reading binary files into a mutable buffer; Network programming: building packet payloads before transmission; Cryptography: assembling mutable byte sequences for encryption algorithms.

Binary file processing, network protocols, cryptography, working with the struct module, or any situation requiring mutable byte sequences.

bytearray_name = bytearray(size)

... = bytearray(...)

bytearray_name: identifier, size: int expression (e.g., 5, len(data))

• memoryview
• struct.pack
• .decode()
• .encode()
• file.readinto()

• bytes(size) for immutable version
• bytearray(b'\x00'*size)

Confusing bytearray with bytes (immutable), forgetting that bytearray elements are ints 0-255, attempting to assign a string directly.

bytes() creates an immutable bytes object; memoryview provides a view without copying.

Coming from languages like C: expecting a pointer or needing to manually manage memory; in Python bytearray manages its own memory.

• bytearray
• bytes
• memoryview
• array.array

The initializer can be an integer (size filled with zeros), an iterable of ints 0-255, or a bytes-like object. Modifying the bytearray in place affects all references.

Provides efficient mutable binary buffer avoiding repeated allocations.

Think 'byte array' as a mutable list of bytes.

bytearray implements the buffer protocol, so it can be passed to C extensions and memoryview without copying, enabling zero‑copy I/O operations.

Using memoryview for zero-copy slicing, or using array module for typed arrays.