4.10 Literals

A literal is a value written directly in source code, as opposed to one computed at runtime — 42, "hello", and True are all literals.

Numeric Literals

>>> type(10)         # int
<class 'int'>
>>> type(10.5)        # float
<class 'float'>
>>> type(1 + 2j)      # complex
<class 'complex'>

String Literals

Covered in depth in Chapter 9: Strings — single, double, and triple quotes all produce str literals.

>>> type("hello")
<class 'str'>

Boolean Literals

>>> type(True)
<class 'bool'>

None

What Is It?

Python’s explicit “no value” placeholder — its own type, distinct from 0, False, or an empty string.

Why Is It Used?

To represent the deliberate absence of a value, e.g. a function that has nothing meaningful to return.

>>> type(None)
<class 'NoneType'>

Collection Literals

>>> type([1, 2])        # list
<class 'list'>
>>> type((1, 2))         # tuple
<class 'tuple'>
>>> type({1, 2})         # set
<class 'set'>
>>> type({"a": 1})       # dict
<class 'dict'>

Quick Interview Answer

“A literal is a value written directly into source code rather than computed — numeric (int, float, complex), string, boolean (True/False), None, and the collection literals [], (), {} for list/tuple/set/dict. None is its own distinct type, NoneType — not the same as 0, False, or "".”

Common Mistakes

• Treating None, 0, False, and "" as interchangeable — they’re all “falsy” in a boolean context, but None specifically represents the absence of a value, not a zero or empty one.
• Writing {} expecting an empty set — {} is actually an empty dict; an empty set requires set().