.to_bytes() in Python

.to_bytes() method is used to convert an integer into its byte representation.This is useful when we need to store or transmit data in binary format.

Example: Convert the integer 10 into bytes.

num = 10
data = num.to_bytes(2, 'little')
print(data) 

b'\n\x00'

Explanation: num.to_bytes(2, 'little') converts integer 10 into 2 bytes using little-endian order.

Note: The byte 0x0A represents decimal 10. Python prints this byte as \n because it corresponds to the newline character.

Syntax

int.to_bytes(length, byteorder, *, signed=False)

Parameters:

• length: The number of bytes the integer should occupy.
• byteorder: The byte order used to represent the integer. It can be: 'big': Most significant byte first (big-endian). 'little': Least significant byte first (little-endian).
• signed: (Optional) If True, allows the representation of negative numbers. Default is False (unsigned).

Return Type: Returns a bytes object representing the integer in the specified format.

Examples

1. Using Little-Endian

num = 10
data = num.to_bytes(2, 'little')
print(data)

b'\n\x00'

Explanation:

• num.to_bytes(2, 'little'): converts 10 into 2 bytes using little-endian order.
• The byte 0x0A represents decimal 10. Python displays it as \n because that is its ASCII character, but it is still the numeric value 10.

2. Representing Negative Numbers

num = -10
data = num.to_bytes(2, 'big', signed=True)
print(data)

b'\xff\xf6'

Explanation:

• Converts -10 into a 2-byte big-endian bytes object using two’s complement.
• signed=True: is necessary to represent negative numbers.

3. Converting Bytes Back to Integer

data = b'\x00\x0a'
num = int.from_bytes(data, 'big')
print(num) 

10

Explanation:

• int.from_bytes(data, 'big'): converts a bytes object back into an integer.
• 'big': Big-endian byte order (most significant byte first).

Related Articles:

• How to Convert Int to Bytes in Python?
• Python bit functions on int (bit_length, to_bytes and from_bytes)