Python basic syntax

1. Naming rules for variables

• Variable names can contain only letters, numbers, and underscores. Variable names can begin with a letter or underscore, but cannot begin with a number, for example, you can name a variable message_1, but you cannot name it 1_message.
• Variable names cannot contain spaces, but you can use underscores to separate words in them. For example, the variable name greeting_message possible, but the variable name greeting message throws an error.
• Do not use Python keywords and function names as variable names, that is, do not reserve words for special purposes using Python, such as print (see Appendix A.4).
• Variable names should be both brief and descriptive. For example, name is better than N, Student_name is better than S_n, Name_length is better than length_of_persons_name.
• Use the lowercase l and the capital Letter o sparingly, as they may be mistaken for numbers 1 and 0.

2, String: is a series of characters. In Python, a string is enclosed in quotation marks, where the quotation marks can be single quotes or double quotes.

' Hello python world! ' " The language ' Python ' is named after Monty Python and not the snake. "

3. Use the method to modify the casing of the string.

1. Title () displays each word in uppercase, with the first letter of each word capitalized.
2. Upper () change each word to uppercase.
3. Lower () Each word is changed to lowercase.

name = ' Tom Frank ' Print (Name.title ())
Print (Name.upper ())
Print (Name.lower ()) Output results: Tom Frank
TOM FRANK
Tom Frank

4. Merging stitching strings

first_name = ' Tom ' Last_naem = ' Frank ' full_name = first_name + ' + last_nameprint (full_name) print ("Hello," + full_name.t Itle () + "!")

5. Add blanks with tabs or line breaks

• Use the character combination \ t to add tabs
• Use character combination \ n, line break

Print ("Languages:\n\tpython\n\tc\n\tjava") output result: Languages:    Python    C    Java

6. Delete Blank

1. Use Rstrip () to remove the trailing blanks

   favorite_languages = ' Python '
   #输出原值
   Print (favprite_langes)
   #去掉末尾空白, Temporary
   Print (Favorit_languages.rstrip ())
   #永久去掉末尾空白
   Favorite_languages = Favorite_languages.rstrip ()
   Print (favorite_languages)

2. Use Lstrip () to remove the beginning blank

   favorite_languages = ' Python ' #输出原值print (favorite_languages) #去掉开头空白, temporary print (Favorite_languages.lstrip ()) # Permanently remove the opening blank favorite_languages = Favorite_languages.lstrip () print (favorite_languages)

3. Use strip () to remove both ends of the blank

   favoriet_languages = ' Pyrhon ' #输出原值print (favorite_languages) #去掉两端空白print (Favorite_languages.strip ())

7. Use the function str () to avoid type errors

Age =  24message = "Happy" +  str (age) + "rd birthday!" Print (message)

Python basic syntax