Python Foundation

• variable

1. Variable type

Variables can specify different data types, which can store integers, decimal or characters.

        2.Variable assignment

• Each variable must be assigned before it is used, and the variable will be created after assignment.
• An equal sign (=) is used to assign variables.
• The equality sign (=) operator has a variable name on the left, and the equality sign (=) operator has a value stored in the variable on the right. For example:

• 1 # autor:guangqing xu
  2 counter =100 #Assigned integer variables
  3 miles = 1000.0 #float
  4 name = "guangqing" #Character
  5 print(counter)
  6 print(miles)
  7 print(name)

  Expression if… Else 

• 1、Scene 1
• # Prompt for user name and password.
    
  # Verify username and password
  #     If it is wrong, the user name or password error is exported.
  #     If successful, output is welcome, XXX!

• 1 # autor:guangqing xu
  2 _username = "guangqing"
  3 _password = "abc123"
  4 username = input("username:")
  5 password = input("password:")
  6 if _username==username and _password==password:
  7     print("Welcome user {name} login...".format(name=username))
  8 else:
  9     print("Invalid username or password!")

   

  1 import getpass
  2 name= raw_input("Please enter user name:")
  3 password = getpass.getpass("Please input a password:")
  4 if name=="guangqing" and password=="abc123":
  5     print("Welcome, Guangqing.")
  6 else:
  7     print("User name and password error")