Variables

Definition

A variable is a named container for a value

Statements

• A statement is a unit of code that the Python interpreter can execute
• Example: print("Hello, world")

Assignment Statement

• Creates or rebinds a variable
• Gives the variable a value

myvar = 42

Variables

• A variable is a named container for a value
• Useful for organizing data flow
• Provide human-readable names for values
• Allow values to be reused

Example

>>> base = 5
>>> height = 6
>>> area = (1 / 2) * base * height
>>> area
15.0

Variable Names

• Should document what the variable is used for
• May include letters and numbers
• Should be lowercase
• May not begin with a number

Reserved Words

Reserved words may not be used as variable names

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

Input Statement

• input(prompt=None)
• Accepts user input as an str (string)
• prompt will be shown to user if provided
• Documentation for input

input Example

user_msg = input("I'm an AI assistant. How may I help you?")

print("It sounds like you'd like help with the following:")
print(user_msg)
print("As an AI assistant, I'm not able to help with that.")

int

• int converts strings to integers

Examples

>>> '12'
'12'
>>> int("12")
12
>>> int("Hello world!")
...ValueError...
>>> int("12.0")
...ValueError...

Comments

• Can be inserted into code as notes for human readers
• Ignored by Python interpreter
• Begin with # symbol

Example Program

# Gather user inputs
base = input("Base:")
height = input("Height:")

# Calculate area result
area = (1 / 2) * int(base) * int(height)

# Display result
print("Area of the triange:")
print(area)