How to Convert Int to Bytes in Python?
The task of converting an integer to bytes in Python involves representing a numerical value in its binary form for storage, transmission, or processing. For example, the integer 5 can be converted into bytes, resulting in a binary representation like b’\x00\x05′ or b’\x05′, depending on the chosen format.
Using int.to_bytes()
.to_bytes() method is the most direct way to convert an integer to bytes. It allows specifying the byte length and byte order (big for big-endian, little for little-endian).
a = 5
res = a.to_bytes(2, 'big') # length: 2 bytes, byte order: Big-endian
print(res)
Output
b'\x00\x05'
Explanation: Here, 2 ensures a fixed 2-byte representation, adding a leading zero-byte (\x00) for padding. ‘big’ specifies big-endian order, storing the most significant byte first.
Table of Content
Using struct.pack()
struct.pack() function is used for packing integers into bytes using format specifiers. The “>H” format specifies a big-endian 2-byte unsigned short, ensuring a structured binary representation.
import struct
a = 5
res = struct.pack(">H", a) # '>H' -> big-endian Unsigned Short (2 bytes)
print(res)
Output
b'\x00\x05'
Explanation: Here, H represents an unsigned short (2 bytes) and > ensures big-endian order, storing the most significant byte first. Since 5 is smaller than 256, a leading zero-byte (\x00) is added for proper 2-byte representation.
Using bytes()
bytes() function can be used to create a single-byte representation of an integer. This method works only for values between 0 and 255 because a single byte can store values in this range.
a = 5
res = bytes([a]) # converts single integer to a 1-byte representation
print(res)
Output
b'\x05'
Explanation:bytes([a]) converts 5 into a 1-byte object since it falls within the 0-255 range, meaning no padding is needed.
Using bytes.fromhex()
This method first converts an integer to a hex string, ensuring it is properly padded and then converts it into a bytes object. It is useful when dealing with hex-based data representation.
a = 5
res = bytes.fromhex(hex(a)[2:].zfill(2)) # ensures 2-digit hex representation
print(res)
Output
b'\x05'
Explanation: hex(a)[2:] removes the 0x prefix, .zfill(2) ensures a 2-digit hex format and bytes.fromhex() converts it into a byte object (b’\x05′) .
