Python3 Bytes API

Introduction

The bytes type in Python3 is used to store a sequence of bytes. It is immutable and represents a sequence of integers in the range 0-255. The bytes type is commonly used to handle binary data, such as reading/writing files or working with network protocols. In this article, we will explore the bytes API in Python3 and see how it can be used in various scenarios.

Creating Bytes Objects

There are several ways to create a bytes object in Python3:

  1. Using a byte literal: Bytes literals are represented by a leading b or B character followed by a string of ASCII characters or escape sequences.
b = b'This is a bytes object'
  1. Using the bytes constructor: The bytes constructor can be used to create a bytes object from a sequence of integers or an iterable of integers.
b = bytes([65, 66, 67])  # create a bytes object from a list of integers
  1. Encoding a string: The encode method can be used to encode a string into a bytes object using a specific encoding.
b = 'Hello, world!'.encode('utf-8')  # encode a string into a bytes object using UTF-8 encoding

Accessing Bytes

Bytes objects can be accessed using the same indexing and slicing techniques as strings. Each byte in the bytes object can be accessed as an integer in the range 0-255.

b = b'Hello, world!'
print(b[0])  # Output: 72
print(b[7:12])  # Output: b'world'

Modifying Bytes

Since bytes objects are immutable, you cannot modify them directly. However, you can create a new bytes object by concatenating or replacing parts of an existing bytes object.

b1 = b'Hello'
b2 = b'world!'
b3 = b1 + b2  # concatenate two bytes objects
print(b3)  # Output: b'Hello, world!'

Converting Bytes to String

To convert a bytes object to a string, you can use the decode method and provide the encoding used to encode the bytes.

b = b'Hello, world!'
s = b.decode('utf-8')  # decode the bytes using UTF-8 encoding
print(s)  # Output: Hello, world!

Common Methods

Bytes objects provide several methods for working with binary data:

  • len(b): Returns the length of the bytes object b.
  • b.hex(): Returns a hexadecimal representation of the bytes object.
  • b.count(sub): Returns the number of non-overlapping occurrences of sub in the bytes object.
  • b.find(sub): Returns the lowest index in the bytes object where sub is found, or -1 if it is not found.
  • b.startswith(prefix): Returns True if the bytes object starts with the specified prefix, otherwise False.

Conclusion

In this article, we explored the bytes API in Python3. We learned how to create, access, and modify bytes objects. We also saw how to convert bytes to strings and use common methods provided by the bytes type. The bytes type is a powerful tool for working with binary data and is widely used in various applications.