You also do not need to pay too much attention to which school is right, just remember the concept of variables in python in one of the two ways above.

Name variable in python

To name variables in python we need to follow Python’s Variable Naming Rule as below:

We will learn more about the Rules of variable naming in Python in the table above as follows

Use alphabet characters, numbers, and underscores to name variables in Python

From Python 3 onwards, we can use kanji and accented Vietnamese to Name variables in python, however Kiyoshi does not recommend this method.

tên = "Kiyoshi"
tuổi =30

名前 = "Kiyoshi"
年齢 = 30

Do not use numeric values ​​for the first character of a variable

We cannot use numeric values ​​for the first character of the variable in python, because a SyntaxError will appear.

7up = 100

Error SyntaxError:

  File "Main.py", line 1
    7up = 100
     ^
SyntaxError: invalid syntax

Case sensitive when naming variables in Python

Case sensitive when Naming variables in python. The two variables in the example below are different and give different results:

str = "I love"
STR = "Vietnam"
print ( str , STR)

>> I love Vietnam

Do not use Python keywords to name variables in python

We can’t use Python keywords to name variables in python. Keywords are Python-only words and you cannot use them to name variables.
You can check the List of keywords in python with the command below.

import sys
import keyword
 
print ("Python version: ", sys.version_info)
print ("Python keywords: ", keyword.kwlist)

And here is the table of keywords in python .

False	await	else	import	pass
None	break	except	in	raise
True	class	finally	is	return
and	continue	for	lambda	try
as	def	from	nonlocal while
assert	del	global	not	with
async	elif	if	or	yield

If you use the keywords in python in the table above to name the variable in Python then the error SyntaxError will return the following example:

from = "Vietnam"

Lỗi SyntaxError:

  File "Main.py", line 1
    from = "Vietnam"
         ^
SyntaxError: invalid syntax

How to use python variables

In the example below, we write a program that calculates the prices (including VAT) of the fruits and prints them on the screen.

print ("Orange price" + str (120 * 1.1))
print ("Apple price" + str (90 * 1.1))
print ("Banana price" + str (100 * 1.1))

If every time we also declare VAT as above, it can be mistaken for carelessness, or in the case of VAT adjustment by the state, we must completely correct it. That is very easy to mistake and costly.

Instead, we’ll use the variable in python by creating a variable tax, then storing the VAT value 1.1in. When using it, we just need to name the variable taxas below:

tax = 1.1 
print ( "Orange price" + str ( 120 * tax)) 
print ( "Apple price" + str ( 90 * tax)) 
print ( "Banana price" + str ( 100 * tax))

Both of the above spellings give the same result:

Orange price 132.0 
Apple 
price 99.00000000000001 Banana price 110.00000000000001

Assuming the state has raised the VAT rate to 1.5times, then simply change the value of the taxcity 1.5

tax = 1.5 
print ( "Orange price" + str ( 120 * tax)) 
print ( "Apple price" + str ( 90 * tax)) 
print ( "Banana price" + str ( 100 * tax))

From the above example, you can see that using variables in python helps us to minimize errors compared to entering values ​​directly, as well as help to change the value of data in the program quickly and efficiently. than.

Summary

Above, Kiyoshi explained what the concept of a variable is in python, how to name a variable in python as well as how to use a variable in python . To better understand the lesson content, practice rewriting today’s examples.

And let’s learn more about Python in the next lessons.

URL Link

https://laptrinhcanban.com/en/python/nhap-mon-lap-trinh-python/bien-trong-python/bien-trong-python-la-gi/

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