Life is short, I use Python's first article

First, the variable name

Custom variable names can only be made up of numbers, letters, and underscores .

Before using a variable, you need to assign a value to the its first

Note: 1. Variable names cannot begin with a number;

2. cannot be a keyword; for example: ' and ', ' as ', ' assert ', ' Break ', ' class ', ' Continue ', ' Def ', ' del ', ' elif ', ' Else ', ' except ', ' exec ',

' Finally ', ' for ', ' from ', ' global ', ' if ', ' import ', ' in ', ' was ', ' lambda ', ' not ', ' or ', ' pass ', ' print ', ' raise ',

' Return ', ' try ', ' while ', ' with ', ' yield '

3. It is best not to duplicate what is built into Python, and two words are best used when writing code, such as Use_name;

About comments: single-line comment # ..... Content..................

Multi-line comment "" "..... Content ... "" "" "" ".

Second, the conditional statement 1.if Basic statement

　　　　If condition:
Internal code block # Internal block code cannot be aligned with if, typically leaving four spaces, i.e. a TAB key
Internal code block
Else
...

Print (' .... ')
For example:
If 1 = = 1:
Print ("Welcome to learn Python")
Print ("Welcome to the blog Park")
　　　　　
Else
Print ("Welcome to Southwest Petroleum University")

2. If support nesting
If 1 = = 1:
If 2 = = 2:
Print (" Welcome to learn python")
Print (" Welcome to the Blog Park ")
Else
Print (" Welcome to Southwest Petroleum University")
Else
Print (" welcome ")

3. If elif

INP = input (' Please enter score: ')

If InP = = "90":
Print (' excellent ')
Elif INP = = "80":
Print (' good ')
Elif INP = = "70":
Print (medium ')
Else
Print (' Pass ')

Print (' ... end ........)

Pass: If nothing is done after the condition, you can use the Pass,pass to empty the code, meaningless, just to represent the code block

For example
If 1==1:
Pass
Else
Print (' SB ')

III. basic data type 1. String

The string we've known so far is everything inside the quotation marks, and we've also called the string text, and the text and numbers are completely different.

To add two numbers and add two characters

Adding quotes to numbers adds up to string concatenation.

When creating a string, enclose the characters in quotation marks, either single quotes, double quotes, or Sanchong quotes, but not mash.

As name = "I am Gio"
name = ' I am Gio '
Name = "" I am Gio "" "
name = ' I am Gio '

For example: Let's go in the input string, and if you use single quotes, you'll get an error.

There are two ways to solve this problem: one is to use double quotes

The second is to escape the quotes in the string using the escape symbol (\)

Note: The string cannot end with \, in the string \ means that the string has not ended, and the newline continues to mean

2. Arithmetic operators

+      -        *      /      %      **      // 

The first four are subtraction.

% means taking remainder

Represents a pickup

* * indicates power

3.while Cycle

While condition:

Action that the condition is true

Dead loop

While 1==1:

Perform actions

Exercises

1. Use while loop input 1 2 3 4 5 6 8 9 10

A=0 while a<10:    a+=1    if a==7 :        pass     else:        print(a)

2. For all numbers of 1-100

a=0s=0 while a<100:    a+=1    s=s+a Print (s)

3. All odd numbers in output 1-100

A=0 while a<100:    a=a+1    if a%2==0:        pass    Else :         Print (a)

4. All even numbers in output 1-100

A=0 while a<100:    a=a+1    if a%2==1:          Pass    else:        print(a)

5, Beg 1-2+3-4+5 ... 99 of all numbers of the and

n = 1                    #  S is the sum of all previous numbers while                     n <:                        = n% 2                        if temp = = 0                            := s -                            nelse                            := s +                                                n= n + 1                                        Print (s)

6. User login (three retry opportunities)

I=0 whileI<3: A= Input ("Please enter user name:")    ifa=="1234":        Print("Login Successful")    Else:        Print("Logon Failure") I=i+1Print("Please try again later .")

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Life is short, I use Python's first article