Python Review

{Review Notes made with W3 Schools}

Syntax

• Indention is important to indicate blocks of codes in Python
• Comments:

  # one line comment 
  
  """ 
  commenting for
  more than 
  one line 
  !
  """ 
  

Variables

• There's no command for declaring a variable, so you can just do x=9
• Variables are created whenever you assign a value to it meaning you don't need to declare it as a type & you're free to change the type after its been created
• If you want to specify the type, you can cast it
• If you want to find the data type of the variable, you can print it with type()
• String variables can be declared with single or double quotes

    # creating variables
    x = 1
    y = "yama"
  
    # casting
    x = (int)1  # 1
    x = (str)1  # '1'
    x = (float)1  # 1.0
  
    # type
    print(type(x))
  
    # string
    x= "yama" 
    x= 'yama'
    # ^ these two are the same
  

Names

• Variable names must start with a letter or underscore - cannot start with numbers
• Variable names are case sensitive (hello, HELLO, Hello)
• Cannot be a python keyword
• Variable name can only contain alpha numeric characters and underscores (A-z, 0-9, and _ )
• Variable naming conversions

  # camelCase
  thisIsCamelCase = "hi"
  
  # PascalCase 
  ThisIsPascalCase = "hello"
  
  # snake_case
  this_is_snake_case = "hey"
  

Multiple Values

• You can assign multiple variables in one line

  x,y,x= "apple", "orange", "cherry"
  

• If you have a list, you can unpack it to extract the values into variables

  fruits= ["apple", "banana", "cherry"]  
  x, y, z = fruits