What Does the \'b\' Prefix Mean in Python Strings?

Understanding the Significance of the 'b' Prefix in Python Strings

In Python source code, you may encounter strings prefixed with a lowercase 'b'. This 'b' signifies a bytes string literal.

Bytes vs. Unicode

In Python 3, strings are predominantly Unicode objects. Unicode strings represent text characters using code points from a wide range of standards, including UTF-8, UTF-16, and UTF-32.

By contrast, bytes objects in Python represent binary data, including encoded text. They contain a sequence of integers in the range 0-255, essentially representing raw data values.

Creating Bytes Objects

To create a bytes object, use the 'b' prefix before a string literal:

<code class="python">b"abcdef"</code>

Alternatively, you can also construct bytes objects from sequences of integers or by encoding Unicode strings:

<code class="python">bytes([72, 101, 108, 108, 111])
bytesvalue = strvalue.encode('utf-8')</code>

Decoding and Encoding

To obtain Unicode text from a bytes object, use the decode() method:

<code class="python">strvalue = bytesvalue.decode('utf-8')</code>

Conversely, to convert Unicode text into bytes, use the encode() method or the bytes object constructor:

<code class="python">bytesvalue = strvalue.encode('utf-8')
bytesvalue = bytes(strvalue, 'utf-8')</code>

Error Handling

Both the decode() and encode() methods accept an optional argument to handle errors during the conversion process. This argument specifies how invalid characters or encoding issues should be managed.

Python 2 Compatibility

Python 2 versions 2.6 and 2.7 also support the 'b' prefix for string literals to facilitate code compatibility with Python 3.

Immutability

Bytes objects are immutable, meaning their content cannot be modified. If you need a mutable representation of binary data, use a bytearray() object instead.

The above is the detailed content of What Does the \'b\' Prefix Mean in Python Strings?. For more information, please follow other related articles on the PHP Chinese website!