Python Byte Strings: What Does the \'b\' Prefix Mean?

Python Byte Strings: What's Behind the "b" Prefix?

In Python, you may encounter strings prefixed with a lowercase "b", as in "b'abcdef'". This prefix signifies a bytes string literal, a different type from regular Unicode strings.

Bytes vs. Unicode Strings

Unicode strings (represented without the "b" prefix) consist of sequences of Unicode code points, essentially representing characters from various languages. In contrast, bytes strings store sequences of integers in the range of 0-255, representing raw binary data or encoded text.

When to Use Bytes Strings

Bytes strings are typically used to model binary data, such as images, audio, or encrypted data. They can also store encoded text, which can later be decoded into Unicode strings using the appropriate codec (e.g., UTF-8).

Creating and Handling Bytes Strings

You can create bytes strings using multiple methods:

• String literals: b'abcdef'
• Bytes constructor: bytes([72, 101, 108, 108, 111]) (where each integer represents a byte)
• Encode function: strvalue.encode('utf-8')

Bytes strings are immutable, meaning you cannot modify their contents. For mutable binary data, use bytearray() objects instead.

Converting Between Bytes and Unicode Strings

To convert a bytes string to a Unicode string, use the decode() method with the appropriate codec:

strvalue = bytesvalue.decode('utf-8')

To convert a Unicode string to a bytes string, use the encode() method:

bytesvalue = strvalue.encode('utf-8')

Compatibility and Usage

Python 2 also supported creating string literals with the "b" prefix. However, in Python 3, it's recommended to use the "b" prefix explicitly when you need bytes strings, as it helps distinguish them from Unicode strings.

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