Shulou(Shulou.com)05/31 Report--

Today, I will talk to you about how to review Python basics. Many people may not know much about it. In order to let you know more, Xiaobian summarized the following contents for you. I hope you can gain something according to this article.

I. Review content

1. Top

interpreter

Coding (2.7 default ascii, 3.6 default utf-8)

2、print（"hello"）2.7

print "hello" 3.6

3. Relationship between codes

ascii unicode (at least two bytes) gbk utf-8

1 byte Minimum 2 bytes 2 Chinese 3 bytes

4, named

Initials, not numbers.

Variable names cannot be keywords

Numeric letters underlined

The meaning of variable existence--> Convenient call

5. Conditions

If conditions:

pass

elif condition:

pass

else：

pass

Note the indentation, colon

6、while

while conditions:

pass Every time the condition is judged to be true, infinite execution

continue Abort this loop and restart the loop

break Terminates all loops

7. Operators

*=

+=

-=

/=

%= remainder

One equal sign is assigned, two equal signs are equal.

num = 13

zq = num % 2 #remainder

if zq == 0：

#Even numbers

else：

#Odd

in Determine if the element is not in the list

num = "zq"

li = ["zq","zw"]

if num in li:

print('zai')

else：

print('buzai')

Add another one to determine whether it starts with z

if num in li and num.startwith（'z'）

# and can add a condition

8. Basic data types

int, plastic

n = 123

n = int(123) # int class--init--

s = "123"

m = int(s) #String type conversion integer

There's a length limit to shaping, 32-bit computers plus or minus 2 to the 31st power...（python2.7）

In Python 3.6, there is no longer a long, no matter how long the number is. 2.7 The inside exceeds the range and converts to long shaping

s = "132sdfg" #String contains only digits

m = int(s)

str, string

s = "zq"

s = str("zq")

a = 123

m = str(a) converts a number to a string

=======

bytes => byte type

str => String

Purpose: byte to string conversion

b = objects of byte type

# m = bytes（b）

m = str（b，encoding="utf-8"）

Start letter capitalization Go space Change case replacement Is it a number, letter beginning and end Search

Number Format Coding Decoding Center Left Floating Right Floating Connection

li = ["zq","ss"]

l1 = "_".join(li)

l1 corresponds to zq_ss

list, list

i = [11,22,33]

i = list(11,22,33) This is wrong

i = list([11,22,33]) list is a class name followed by parentheses. There can only be one element inside, but it must be enclosed in brackets and sequence.

=====

t = (11,22,33)

i = list([t]) This is wrong and the result is [(11,22,33)]

i = list(t) This is correct

t = [11,22,33]

t = [11, 22, 33,] These two are similar.

Common functions of lists:

index

slice

for

length

enumerate

Delete del li[0]

del li[0:2]

Unique functions:

flip

sort

additional

inserted

index position

delete

pop

extended

clear

tuple：

t = (11,22,33,44)

t = tuple(iterable object)

li = (11,22,33,44)

l1 = tuple(li)

Public functions:

index

slice

for

length

enumerate

in

Unique functions:

number

index position

Feature: Cannot modify...

dict：

d = {"k":123,"k2":65}

d2 = {

"k":123,

"k2":156

}

li = [1,2,3,4]

Dictionary: key: 10 increments

value: element of the list

dic = []

for i,j in enumerate(li,10):

new_dict = dict(enumerate(li,10))

Public functions:

index

Add dic[key]=vlue

delete

for

length

in

Unique functions:

Get Haskey--> is

update

fromkey

String, byte

str

bytes

a = bytes encoded by "zhang qiang" gbk

b = bytes(a,encoding="gbk") type(b)=> bytes

c = str(b,encoding="gbk")

int optimization mechanism

a = 123

b = 123

id(a)

Same, because there are optimizations,-5 to 257

a = 123

b = a

After reading the above, do you have any further understanding of how to do python fundamentals review? If you still want to know more knowledge or related content, please pay attention to the industry information channel, thank you for your support.

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