Comprehensive Guide to Python Built-in Functions with Examples

Python Built-in Functions Overview

Python provides a set of built‑in functions that can be used directly without importing any modules, such as print() and input() . Up to version 3.6.2, there are 68 built‑in functions, which are listed below.

<code>abs()           dict()          help()          min()           setattr()
all()           dir()           hex()           next()          slice()
any()           divmod()        id()            object()        sorted()
ascii()         enumerate()    input()         oct()           staticmethod()
bin()           eval()         int()           open()          str()
bool()          exec()         isinstance()    ord()           sum()
bytearray()     filter()       issubclass()    pow()           super()
bytes()         float()        iter()          print()         tuple()
callable()      format()       len()           property()      type()
chr()           frozenset()    list()          range()         vars()
classmethod()  getattr()      locals()        repr()          zip()
compile()       globals()      map()           reversed()      __import__()
complex()       hasattr()      max()           round()
delattr()      hash()        memoryview()    set()
</code>

Numeric Related Functions

1. Data Types

bool – Boolean type (True, False)

int – Integer type

float – Floating‑point type

complex – Complex number type

2. Base Conversions

bin() – Convert to binary

oct() – Convert to octal

hex() – Convert to hexadecimal

<code>print(bin(10))   # 二进制:0b1010
print(hex(10))   # 十六进制:0xa
print(oct(10))   # 八进制:0o12
</code>

3. Mathematical Operations

abs() – Absolute value

divmod() – Quotient and remainder

round() – Round to nearest

pow(a, b[, mod]) – Power (optional modulo)

sum() – Sum of iterable

min() – Minimum value

max() – Maximum value

<code>print(abs(-2))                # 2
print(divmod(20, 3))          # (6, 2)
print(round(4.51))             # 5
print(pow(10, 2, 3))          # 1
print(sum([1,2,3,4,5,6,7,8,9,10])) # 55
print(min(5,3,9,12,7,2))      # 2
print(max(7,3,15,9,4,13))     # 15
</code>

Data Structure Related Functions

1. Sequences

(1) Lists and tuples

list() – Convert an iterable to a list

tuple() – Convert an iterable to a tuple

<code>print(list((1,2,3,4,5,6)))   # [1, 2, 3, 4, 5, 6]
print(tuple([1,2,3,4,5,6]))   # (1, 2, 3, 4, 5, 6)
</code>

(2) Related functions

reversed() – Return an iterator that yields items in reverse order

slice() – Create a slice object for list slicing

<code>lst = "你好啊"
it = reversed(lst)
print(list(it))   # ['啊', '好', '你']

lst = [1,2,3,4,5,6,7]
print(lst[1:3])   # [2, 3]
s = slice(1,3,1)
print(lst[s])     # [2, 3]
</code>

2. Collections

dict() – Create a dictionary

set() – Create a set

frozenset() – Create an immutable set

3. Collection Helpers

len() – Number of items

sorted() – Return a new sorted list

enumerate() – Enumerate items with indices

all() – True if all items are true

any() – True if any item is true

zip() – Aggregate elements from multiple iterables

filter() – Filter items using a predicate

map() – Apply a function to each item

<code># sorted example
lst = [5,7,6,12,1,13,9,18,5]
lst.sort()
print(lst)          # [1, 5, 5, 6, 7, 9, 12, 13, 18]
print(sorted(lst, reverse=True))  # [18, 13, 12, 9, 7, 6, 5, 5, 1]

# enumerate example
for index, el in enumerate(['one','two','three'], 1):
    print(index, el)

# filter example
def is_odd(i):
    return i % 2 == 1
print(list(filter(is_odd, range(1,10))))  # [1, 3, 5, 7, 9]

# map example
print(list(map(lambda x: x*2, [1,2,3])))  # [2, 4, 6]
</code>

Scope Related Functions

locals() – Return a dictionary of the current local symbol table

globals() – Return a dictionary of the current global symbol table

<code>def func():
    a = 10
    print(locals())   # {'a': 10}
    print(globals())  # {...}
func()
</code>

Iterator & Generator Functions

range() – Generate a sequence of numbers

next() – Retrieve the next item from an iterator

iter() – Get an iterator from an iterable

<code>for i in range(15, -1, -5):
    print(i)   # 15 10 5 0

lst = [1,2,3,4,5]
it = iter(lst)
print(next(it))   # 1
print(it.__next__()) # 2
</code>

String Execution Functions

eval() – Evaluate a string as an expression and return the result

exec() – Execute a string as Python code (no return value)

compile() – Compile source code into a code object

<code>s1 = input("请输入 a+b:")   # e.g., 8+9
print(eval(s1))               # 17
s2 = "for i in range(5): print(i)"
exec(s2)                       # prints 0‑4

code = "for i in range(3): print(i)"
com = compile(code, "", mode="exec")
exec(com)                      # 0 1 2
</code>

Input/Output Functions

print() – Output to console

input() – Read user input

<code>print("hello", "world", sep="*", end="@")   # hello*world@
</code>

Memory‑Related Functions

hash() – Return the hash value of an object

id() – Return the memory address of an object

<code>s = "alex"
print(hash(s))   # e.g., -168324845050430382
print(id(s))     # e.g., 2278345368944
</code>

File Operations

open() – Open a file and return a file object

<code>f = open('file', mode='r', encoding='utf-8')
content = f.read()
f.close()
</code>

Module Handling

__import__() – Dynamically import a module by name

<code>name = input("请输入你要导入的模块:")
__import__(name)
</code>

Utility Functions

help() – Show the help page for an object

callable() – Check if an object appears callable

dir() – List the attributes of an object

<code>print(help(str))
print(callable(10))   # False
print(dir(tuple))
</code>