Python basic syntax

1. View the Python version

Python-v

The results of the above command execution are as follows:

2. Identifiers

• The first character must be a letter in the alphabet or an underscore _.
• The other parts of the identifier are made up of letters, numbers, and underscores.
• Identifiers are case sensitive.

3.python reserved words

Reserved words are keywords, and we cannot use them as any identifier names. Python's standard library provides a keyword module that can output all the keywords for the current version:

Import keyword>>> keyword.kwlist

' From ', ' global ', ' if ', ' Import ', ' on ', ' is ', ' lambda ', ' nonlocal ', ' no ', ' or ', ' Pass ', ' raise ', ' return ', ' try ', ' while ' , ' with ', ' yield ']

4. Notes

The single-line comment in Python begins with # , with the following example:

# First comment Print ("Hello, python! ")  

Multiline comments can be in multiple # numbers, plus " and " ":

# First comment # a second comment " " Third Note IV " " """ Fifth note Sixth Comment """ Print ("Hello, python! "

5. Line and indent

Python's most distinctive feature is the use of indentation to represent blocks of code, without the need to use curly braces {}.

The number of spaces to indent is variable, but the statement of the same code block must contain the same number of indentation spaces.

if True:     Print ('True') Else :     Print ('False')

The following code does not match the number of spaces in the last line of the statement, resulting in a run error:

ifTrue:Print('C')    Print('C #')Else:    Print('python')   Print('Java')#Inconsistent indentation, resulting in a run error

Error: Indentationerror:unindent does not match no outer indentation level

Add: The If else argument does not write "()", the single must write ":"

6. Multi-line statements

Python is usually a line to finish a statement, but if the statement is long, we can use a backslash (\) to implement a multiline statement

" item_one          item_two          item_three"

Multi-line statements in [], {}, or () do not need to use backslashes (\)

Total = ['one',         'both ',          'three'

7. Wait for user input

temp = input ('\ n Please enter content:')print(temp)

\ nthe output of a new blank line before the result output

8. Display multiple statements on the same line

Python can use multiple statements in the same row, using semicolons between statements (;) split

Import ' Runoob ' ' \ n ' )#  output: Runoob

9.Print output

The print default output is newline, and if you want to implement no newline, add end= ""to the end of the variable:

"  One "  "both"#  newline output print(string1)print  (string2)#  non-newline output print(string1,end="" )print(string2)

10.import and From...import

Import the appropriate modules in Python using Import or from...import.

Import the entire module (turtle) in the format: import Turtle

Import a function from a module in the format: from turtle import done

Import multiple functions from a module in the format: from turtle import done,deepcopy

Import all functions in a module in the format: from turtle Import *

Import Turtle  from Import  Done  from Import done,deepcopy  from Import *

11. Command-line arguments

Many programs can perform some operations to see some basic information, Python can use the-H parameter to view the parameters Help information

Python basic syntax