Detailed explanation of python's basic data types

This article mainly shares with you a detailed explanation of the basic data types of Python. Friends who need it can take a look at

This article This article mainly shares with you a detailed explanation of the basic data types of python. Friends who need it can take a look.

How to run python files

1. Python’s own shell

2. Go to the directory where the python file is located, Then run
   python xxx.py (such as C:\work>python hello.py)

3.pythoncharm and other IDE

4.sublime Text etc. Plug-in editor

Data type

Python data types are divided into variable types and immutable types

Python basic data types

The variable type is

Number (number):

Including int, float, bool, complex (plural).

Note:

1. Python can assign values ​​to multiple variables at the same time, such as a, b = 1, 2.

2. A variable can point to objects of different types through assignment.

3. The division of numerical values ​​(/) always returns a floating point number. To obtain an integer, use the // operator.

4. During mixed calculation, Python will convert integers into floating point numbers.

5. Power a**b

6. Complex number a+bj or complex(a,b)

String (string):

List (list)

Dictionary (dictionary)

Sets (set)

A set (set) is an unordered sequence of non-repeating elements.
The basic function is to perform membership testing and remove duplicate elements.
You can use curly brackets { } or the set()

function to create a set. Note: To create an empty set, you must use set() instead of { }, because { } is used to create an empty dictionary.

#!/usr/bin/python3student = {'Tom', 'Jim', 'Mary', 'Tom', 'Jack', 'Rose'}

print(student)   # 输出集合，重复的元素被自动去掉# 成员测试if('Rose' in student) :
    print('Rose 在集合中')else :
    print('Rose 不在集合中')# set可以进行集合运算a = set('abracadabra')
b = set('alacazam')

print(a)

print(a - b)     # a和b的差集print(a | b)     # a和b的并集print(a & b)     # a和b的交集print(a ^ b)     # a和b中不同时存在的元素

The immutable type is

Tuple (tuple)

1. List content

Constructing a tuple containing 0 or 1 elements is special

tup1 = ()    # 空元组tup2 = (20,) # 一个元素，需要在元素后添加逗号

==Tuples can also be spliced ​​using the + operator. ==

The so-called "unchanged" of tuple means that each element of tuple points to the same forever

>>> t = ('a', 'b', ['A', 'B'])
>>> t[2][0] = 'X'
>>> t[2][1] = 'Y'
>>> t
('a', 'b', ['X', 'Y'])

---

==python Description of variables==

The declaration of a python variable is a reference to an object. For a variable type, if its copy changes, it itself will also change

>>> a
[1]>>> a=b=[]>>> a
[]>>> b
[]>>> b.append(0)>>> b
[0]>>> a
[0]>>>

For immutable types Type, its variable value will not be affected by the copy

>>> a=b=(1,2,3)>>> a
(1, 2, 3)>>> b
(1, 2, 3)>>> b+(4,)
(1, 2, 3, 4)>>> b
(1, 2, 3)>>> b=b+(4,)>>> b
(1, 2, 3, 4)>>> a
(1, 2, 3)

Python data type conversion

##tuple(s)Convert sequence s into a tuplelist(s)Convert sequence s into a listset(s)Convert to a variable setdict(d)Create a dictionary. d must be a sequence of (key, value) tuples. frozenset(s)Convert to immutable collectionchr(x)Convert an integer to a characterord( x)Convert a character to its integer valuehex(x)Convert an integer to a hexadecimal stringoct(x)Convert an integer to an octal stringRelated recommendations:

Function	Description
int(x [,base])	Convert x to an integer
float(x)	Convert x to a floating point number
complex(real [ ,imag])	Create a plural number
##str(x)	Convert object x to string
repr(x)	Convert object x to expression The formula string
eval(str)	is used to evaluate the valid Python expression in the string, And return an object

Python’s basic data types

Python common data types and common operations

Detailed introduction to Python basic data types

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