4.3 variables and assignments

4.3 Variables and assignments

4.3.1 Concept of variables

Variable , That is, the amount of change , It can be understood as a container .
This container can hold （ Storage ） All kinds of things （ data ）, And things can be changed , There are many containers for storing different data in the computer , To distinguish between different containers , We need to name these containers , That's variable name , We can access variables by their names .
The four cans in the picture below are the four containers , Four variables .
Depending on the food stored , We can name them canned strawberries 、 Canned cherry 、 Canned grapes 、 Canned oranges . In this way, you can get the specific variable through the variable name .

4.3.2 The assignment of a variable

stay Python in , The assigned symbol is =.
= It doesn't mean the left is equal to the right , stay Python in = Is the meaning of assignment , It means that = The content on the right is put in = In the container on the left .
Canned strawberries = strawberry
Put strawberries in a can of strawberries .

stay Python in , The equals sign is ==.

4.3.3 Assign a value to a variable

#  A variable called name, =  It means assignment , Andy is a variable name Stored content 
name = ' Andy '

#  Check the variable name Stored content 
name 

' Andy '

【 Andy 】 Is the character , You need quotation marks before and after assigning values to variables .

#  A variable called age, =  It means assignment ,25 It's a variable. name Stored content 
age = 25

#  Check the variable age Stored content 
age

25

【25】 to age When assigning values, you can use quotation marks to represent the string type , You can do it without quotes , It's an integer .

#  Assign a value to a variable 
number_1 = 10 
number_2 = 10

# print Function to view variables 
print(number_1)
print(number_2)

10
10

stay Python Two variables are equal ：
number_1 == number_2

4.3.4 Variable naming conventions

1、 Variable names must be alphabetic or underlined _ Start , Don't start with numbers ;
2、 Try to describe the data contained ; If the name is name, Age use age, You can see what variables store at a glance , Convenient to call ;
3、 Do not use what you will learn in the future Python Keywords in ;
4、 Variable names are case sensitive ,name and Name Represents two different variables .

#  To the variable age  First assignment 
age = 25

#  To the variable age  The second assignment 
age = 20

#  To the variable age  The third assignment 
age = 10

# see age
age 

10

The above code we give age Assign three times , The final output is the third assignment ;
stay Python in , The final value of the variable is equal to the last assignment of the variable .

4.3.5 summary

1、= It means assigning values to variables ;
2、== It means equal to ;
3、 The final value of the variable is equal to the final assignment .