Unlock Python’s 68 Built‑in Functions: A Complete Guide for Beginners

Python provides 68 built‑in functions (up to version 3.6.2) that can be used directly, such as print, input, and many others.

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()

Related to Numbers

1. Data Types

bool: Boolean type (True, False)

int: Integer type

float: Floating‑point type

complex: Complex number type

2. Base Conversion

bin()

converts a value to binary oct() converts a value to octal hex() converts a value to hexadecimal

print(bin(10))   # binary: 0b1010
print(hex(10))   # hexadecimal: 0xa
print(oct(10))   # octal: 0o12

3. Mathematical Operations

abs()

returns absolute value divmod() returns quotient and remainder round() rounds a number pow(a, b[, c]) computes aⁿ, optionally modulo c sum() returns the sum of an iterable min() returns the smallest value max() returns the largest value

print(abs(-2))               # 2
print(divmod(20, 3))        # (6, 2)
print(round(4.50))          # 4
print(round(4.51))          # 5
print(pow(10, 2, 3))        # 1 (10² mod 3)
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

Related to Data Structures

1. Sequences

(1) Lists and tuples list() converts an iterable to a list tuple() converts an iterable to a tuple

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)

(2) Related built‑ins reversed() returns an iterator that yields items in reverse order slice() creates a slice object for list slicing

lst = "你好啊"
it = reversed(lst)   # returns an iterator, original unchanged
print(list(it))      # ['啊', '好', '你']
lst = [1,2,3,4,5,6,7]
print(lst[1:3:1])    # [2, 3]
s = slice(1, 3, 1)
print(lst[s])         # [2, 3]

(3) Strings str() converts a value to a string

print(str(123) + '456')   # 123456
print(format('hello world!', '^20'))   # centered
print(format('hello world!', '<20'))   # left‑aligned
print(format('hello world!', '>20'))   # right‑aligned
print(format(3, 'b'))   # binary: 11
print(format(97, 'c'))  # unicode character: a
print(format(11, 'x'))  # hex (lowercase): b
print(format(11, 'X'))  # hex (uppercase): B
print(format(11, 'e'))  # scientific notation: 1.100000e+01

bytes()

converts a string to a bytes object bytearray() creates a mutable byte array ord() returns the Unicode code point of a character chr() returns the character for a Unicode code point ascii() returns a printable representation of an object repr() returns the string representation that can be evaluated

bs = bytes("今天吃饭了吗", encoding="utf-8")
print(bs)   # b'...'
ret = bytearray("alex", encoding='utf-8')
print(ret[0])   # 97
print(ret)      # bytearray(b'alex')
ret[0] = 65
print(str(ret))  # bytearray(b'Alex')
print(ord('a'))   # 97
print(chr(65))   # A
print(ascii('@')) # '@'

2. Collections

dict()

creates a dictionary set() creates a set frozenset() creates an immutable set

3. Collection Utilities

len()

returns the number of items sorted() returns a new sorted list; optional key and reverse arguments enumerate() yields (index, element) pairs all() returns True if every element is truthy any() returns True if at least one element is truthy zip() aggregates elements from multiple iterables into tuples filter() filters an iterable using a predicate function map() applies a function to each element of an iterable

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]

lst = ['one','two','three','four','five','six']
print(sorted(lst, key=len))   # ['one','two','six','four','five','three']

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

print(all([1,'hello',True,9]))   # True
print(any([0,0,0,False,1,'good']))   # True

lst1 = [1,2,3,4,5,6]
lst2 = ['A','B','C','D','E','F']
lst3 = ['US','CN','FR','IT','KR','JP']
for el in zip(lst1, lst2, lst3):
    print(el)

def is_odd(i):
    return i % 2 == 1
lst = [1,2,3,4,5,6,7,8,9]
print(list(filter(is_odd, lst)))   # [1,3,5,7,9]

def identity(i):
    return i
print(list(map(identity, [1,2,3,4,5,6,7])))   # [1,2,3,4,5,6,7]

Related to Scope

locals()

returns a dictionary of the current local symbol table globals() returns a dictionary of the current global symbol table

def func():
    a = 10
    print(locals())   # {'a': 10}
    print(globals())  # {...}
    print("今天内容很多")
func()

Related to Iterators and Generators

range()

generates a sequence of numbers iter() obtains an iterator from an iterable next() advances an iterator

for i in range(15, -1, -5):
    print(i)   # 15 10 5 0
lst = [1,2,3,4,5]
it = iter(lst)
print(it.__next__())   # 1
print(next(it))        # 2
print(next(it))        # 3
print(next(it))        # 4

Executing Code from Strings

eval()

evaluates a string as an expression and returns the result exec() executes a string as a block of statements compile() compiles source code to a code object that can be executed with exec or evaluated with

eval

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)"
obj = compile(code, "", mode="exec")
exec(obj)                     # 0 1 2
expr = "5+6+7"
obj2 = compile(expr, "", mode="eval")
print(eval(obj2))              # 18

Input and Output

print()

outputs data to the console input() reads a line from standard input

print("hello", "world", sep="*", end="@")   # hello*world@

Memory Related

hash()

returns the hash value of an object (int, str, bool, tuple). Hash tables give dictionaries fast look‑ups but require extra memory.

s = "alex"
print(hash(s))   # e.g., -168324845050430382
print(id(s))     # memory address of the object

File Operations

open()

opens a file and returns a file object

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

Modules

__import__()

imports a module dynamically

import os
name = input("请输入你要导入的模块:")
__import__(name)   # dynamically imports the specified module

Help

help()

displays the documentation of an object

print(help(str))   # shows help for the str type

Calling

callable()

checks whether an object appears callable

a = 10
print(callable(a))   # False

def f():
    print("hello")
print(callable(f))   # True

Inspect Built‑in Attributes

dir()

lists the attributes of an object

print(dir(tuple))   # shows methods of the tuple type