Why Does Python Use the \"u\" Symbol Before String Values?

Why the 'u' Symbol Precedes String Values

When you encounter the 'u' symbol before string values in your Python script, it signifies Unicode strings. Unicode is a comprehensive character encoding standard that extends beyond the limitations of ASCII, enabling the representation of a wider range of characters.

In Python 2, the 'u' prefix distinguishes Unicode strings from regular strings. This distinction is absent in Python 3, where Unicode strings are the default.

Unicode Representation

Unicode allows for the representation of characters from different languages and symbols. For instance:

<code class="python">val = u'Ознакомьтесь с документацией'</code>

This Unicode string stores Russian characters, effectively allowing you to embed non-English characters in your code.

Unicode Compatibility

In Python 2, Unicode and non-Unicode strings behave similarly. For example:

<code class="python">bird1 = unicode('unladen swallow')
bird2 = 'unladen swallow'

bird1 == bird2  # True</code>

However, this interchangeability is not guaranteed in Python 3. In Python 3, you must explicitly distinguish between Unicode strings and byte strings, using prefixes such as 'u' for Unicode and 'b' for bytes.

Additional Symbols

Besides the 'u' symbol, you may encounter other special characters in Python strings:

• r: Indicates a "raw" string, preventing backslash escapes from being interpreted.

Example

<code class="python">'foo\&quot;'  # Regular string with interpreted backslashes
r'foo\&quot;'  # Raw string with literal backslashes</code>

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