Built-in Functions

Python's built-in functions are available without importing any modules. This reference covers all built-in functions with their parameters, return values, and practical usage examples.

Mathematical Functions

Function	Purpose	Parameters	Return Type	Example	Description
abs()	Absolute value	`abs(x)`	Number	`abs(-5) # 5`	Returns absolute value of a number
divmod()	Division and modulo	`divmod(a, b)`	Tuple	`divmod(10, 3) # (3, 1)`	Returns quotient and remainder
max()	Maximum value	`max(iterable)` or `max(a, b, ...)`	Any	`max([1, 5, 3]) # 5`	Returns largest item
min()	Minimum value	`min(iterable)` or `min(a, b, ...)`	Any	`min([1, 5, 3]) # 1`	Returns smallest item
pow()	Power operation	`pow(base, exp, mod=None)`	Number	`pow(2, 3) # 8`	Returns base raised to power
round()	Round number	`round(number, ndigits=None)`	Number	`round(3.14159, 2) # 3.14`	Rounds to specified decimal places
sum()	Sum of sequence	`sum(iterable, start=0)`	Number	`sum([1, 2, 3]) # 6`	Returns sum of all items

Type Conversion Functions

Function	Purpose	Parameters	Return Type	Example	Description
bool()	Convert to boolean	`bool(x)`	bool	`bool(1) # True`	Converts value to boolean
int()	Convert to integer	`int(x, base=10)`	int	`int("123") # 123`	Converts to integer
float()	Convert to float	`float(x)`	float	`float("3.14") # 3.14`	Converts to floating point
str()	Convert to string	`str(object)`	str	`str(123) # "123"`	Converts to string representation
list()	Convert to list	`list(iterable)`	list	`list("abc") # ['a', 'b', 'c']`	Converts iterable to list
tuple()	Convert to tuple	`tuple(iterable)`	tuple	`tuple([1, 2, 3]) # (1, 2, 3)`	Converts iterable to tuple
set()	Convert to set	`set(iterable)`	set	`set([1, 2, 2, 3]) # {1, 2, 3}`	Converts iterable to set
dict()	Create dictionary	`dict(**kwargs)`	dict	`dict(a=1, b=2) # {'a': 1, 'b': 2}`	Creates dictionary
bytes()	Convert to bytes	`bytes(source, encoding)`	bytes	`bytes("hello", "utf-8")`	Converts to bytes object

Sequence and Iteration Functions

Function	Purpose	Parameters	Return Type	Example	Description
len()	Get length	`len(s)`	int	`len([1, 2, 3]) # 3`	Returns length of sequence
range()	Create range	`range(start, stop, step)`	range	`list(range(5)) # [0, 1, 2, 3, 4]`	Creates sequence of numbers
enumerate()	Add indices	`enumerate(iterable, start=0)`	enumerate	`list(enumerate(['a', 'b'])) # [(0, 'a'), (1, 'b')]`	Returns indexed pairs
zip()	Combine iterables	`zip(*iterables)`	zip	`list(zip([1, 2], ['a', 'b'])) # [(1, 'a'), (2, 'b')]`	Combines multiple iterables
reversed()	Reverse sequence	`reversed(seq)`	iterator	`list(reversed([1, 2, 3])) # [3, 2, 1]`	Returns reversed iterator
sorted()	Sort sequence	`sorted(iterable, key=None, reverse=False)`	list	`sorted([3, 1, 2]) # [1, 2, 3]`	Returns sorted list
filter()	Filter items	`filter(function, iterable)`	filter	`list(filter(lambda x: x > 0, [-1, 0, 1, 2])) # [1, 2]`	Filters items by function
map()	Apply function	`map(function, iterable)`	map	`list(map(str.upper, ['a', 'b'])) # ['A', 'B']`	Applies function to each item
any()	Test any true	`any(iterable)`	bool	`any([False, True, False]) # True`	True if any element is true
all()	Test all true	`all(iterable)`	bool	`all([True, True, False]) # False`	True if all elements are true

Object and Attribute Functions

Function	Purpose	Parameters	Return Type	Example	Description
getattr()	Get attribute	`getattr(object, name, default=None)`	Any	`getattr(obj, 'attr', 'default')`	Gets object attribute safely
setattr()	Set attribute	`setattr(object, name, value)`	None	`setattr(obj, 'attr', 'value')`	Sets object attribute
hasattr()	Check attribute	`hasattr(object, name)`	bool	`hasattr(obj, 'attr') # True/False`	Checks if object has attribute
delattr()	Delete attribute	`delattr(object, name)`	None	`delattr(obj, 'attr')`	Deletes object attribute
callable()	Check callable	`callable(object)`	bool	`callable(len) # True`	Checks if object is callable
isinstance()	Check instance	`isinstance(object, classinfo)`	bool	`isinstance([], list) # True`	Checks object type
issubclass()	Check subclass	`issubclass(class, classinfo)`	bool	`issubclass(bool, int) # True`	Checks class inheritance
type()	Get type	`type(object)`	type	`type([]) # <class 'list'>`	Returns object type
id()	Get object ID	`id(object)`	int	`id([]) # 140234567890`	Returns unique object identifier
vars()	Get variables	`vars(object=None)`	dict	`vars(obj) # {'attr': 'value'}`	Returns object's `__dict__`

Input/Output Functions

Function	Purpose	Parameters	Return Type	Example	Description
print()	Print output	`print(*values, sep=' ', end='\n', file=sys.stdout)`	None	`print("Hello", "World")`	Prints values to output
input()	Get user input	`input(prompt='')`	str	`name = input("Name: ")`	Gets string input from user
open()	Open file	`open(file, mode='r', encoding=None)`	file object	`open('file.txt', 'r')`	Opens file for reading/writing

Advanced Functions

Function	Purpose	Parameters	Return Type	Example	Description
eval()	Evaluate expression	`eval(expression, globals=None, locals=None)`	Any	`eval("2 + 3") # 5`	Evaluates Python expression
exec()	Execute code	`exec(object, globals=None, locals=None)`	None	`exec("x = 5")`	Executes Python code
compile()	Compile code	`compile(source, filename, mode)`	code object	`compile("x + 1", "", "eval")`	Compiles source into code object
globals()	Global namespace	`globals()`	dict	`globals()['__name__']`	Returns global symbol table
locals()	Local namespace	`locals()`	dict	`locals()`	Returns local symbol table
dir()	List attributes	`dir(object=None)`	list	`dir([]) # ['append', 'clear', ...]`	Lists object attributes
help()	Get help	`help(object=None)`	None	`help(len)`	Shows help documentation
hash()	Get hash	`hash(object)`	int	`hash("hello") # 2314058222102390712`	Returns object hash value
iter()	Create iterator	`iter(object, sentinel=None)`	iterator	`iter([1, 2, 3])`	Creates iterator object
next()	Get next item	`next(iterator, default=None)`	Any	`next(iter([1, 2, 3])) # 1`	Gets next item from iterator
repr()	String representation	`repr(object)`	str	`repr([1, 2, 3]) # "[1, 2, 3]"`	Returns string representation
ascii()	ASCII representation	`ascii(object)`	str	`ascii("café") # "'caf\\xe9'"`	Returns ASCII string representation
bin()	Binary representation	`bin(x)`	str	`bin(10) # '0b1010'`	Converts integer to binary string
hex()	Hexadecimal representation	`hex(x)`	str	`hex(255) # '0xff'`	Converts integer to hex string
oct()	Octal representation	`oct(x)`	str	`oct(8) # '0o10'`	Converts integer to octal string
ord()	Character code	`ord(c)`	int	`ord('A') # 65`	Returns Unicode code of character
chr()	Character from code	`chr(i)`	str	`chr(65) # 'A'`	Returns character from Unicode code

Memory and Object Functions

Function	Purpose	Parameters	Return Type	Example	Description
object()	Create object	`object()`	object	`obj = object()`	Creates new object instance
super()	Parent class access	`super(type=None, object=None)`	super	`super().__init__()`	Access parent class methods
property()	Create property	`property(fget=None, fset=None, fdel=None, doc=None)`	property	`prop = property(getter, setter)`	Creates property descriptor
staticmethod()	Static method	`staticmethod(function)`	staticmethod	`@staticmethod`	Creates static method
classmethod()	Class method	`classmethod(function)`	classmethod	`@classmethod`	Creates class method

Best Practices

Use type conversion functions: Prefer int(), str(), etc. over manual conversion
Leverage sequence functions: Use enumerate(), zip(), sorted() for cleaner code
Check before accessing: Use hasattr() before getattr() for safety
Prefer built-ins: Built-in functions are optimized and typically faster
Know your iterators: Understand the difference between map(), filter(), and list comprehensions
Use any() and all(): More readable than manual loops for boolean testing

Online Python

Built-in Functions

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