Python Basics: Variables and Data Types

Getting Started with Python

• Getting started with Python can be done in less than 10 minutes
• Python 3.8 is used
• PyCharm is used as the code editor
• Python and PyCharm are freely available

Variables in Python

• Variables are created by assigning a value to a name/identifier
• item = "banana" assigns the string "banana" to the variable named item
• Strings are any form of text
• Python is case-sensitive, item and Item are different variables
• Naming convention: use underscores for multi-word variable names (e.g. item_name)
• item_name = "orange" assigns the string "orange" to the variable item_name
• Different strings can be combined using the + operator
• "Hello" + item_name results in "Hello orange"

Data Types in Python

• Integer: Any number (e.g., 2021)
• String: Any text inside quotation marks (e.g., "text")
• Boolean: True or False values
• List: A collection of values inside angle brackets (e.g., [“string1”, “string2”, “string3”])

Combining Different Data Types

• Different data types such as strings and integers need to be converted before concatenating
• Converting an integer to a string: str(integer_variable)
• name + str(integer_variable) combines the string name with the string representation of integer_variable
• Converting a string containing a number to an integer:
• int(string_number) + 10 converts string_number to an integer and adds 10

Math Operators

• Addition: + symbol
• Subtraction: - symbol
• Multiplication: * symbol
• Division: / symbol
• Exponential power: ** symbol
• Example: a = 10, b = 5
  • a + b (addition): 15
  • a - b (subtraction): 5
  • a * b (multiplication): 50
  • a / b (division): 2.0
  • a ** b (exponential power): 100000

Logic Statements

• if, elif, and else statements control the flow of logic in a program
• if age > 21: print("You are old")
• elif age == 18: print("You are getting old")
• else: print("You are still young")
• The if statement checks whether a condition (e.g. is_happy == True) is met
• if is_happy: print("You are happy")
• else: print("You are not happy")

For Loops

• For loops are used to iterate over a range or collection of values
• for i in range(3): print("hello", i) will execute the print statement three times
• The range(3) function creates a sequence of number starting from 0, thus resulting in "hello 0, hello 1, hello 2.
• To start the index at one, increment the variable i by one i + 1
• To iterate over a list: create a list and loop over it
• name_list = ["Mario", "Luigi", "Peach"] then for name in name_list: print(name)

While Loops

• While loops execute as long as the condition is true
• i = 0
• while i < 5: i += 1; print(i) prints values from 1 to 5
• Infinite loop: while True:
• user_input = input("Enter something:") gets input from the user
• if user_input == "0": print("We are done here"); break; will break the loop as soon as the user types 0
• break statement exits the loop

Functions

• Functions are reusable blocks of code
• def keyword is used to define a function
• Naming convention for functions: use underscores
• def say_hello_to_user(name): print("Hey there", name)
• pass keyword: When a function has no logic use the pass keyword to avoid getting an error
• Functions are called like so:
  • def get_internet(): pass
  • def run_game(): pass

Try and Except Block

• Handle exceptions
• Execute code in the try block
• If any exception occurs, the code inside the except block will execute
• number = input("Please provide a number: ")
• try: print(10 + int(number))
• except: print("That is not a valid number")

Explore the fundamentals of Python, including setting up the environment and understanding variables. Learn how to assign values to variables, the importance of case sensitivity, and naming conventions. Discover basic data types: integers, strings, booleans, and lists.