Python Variables
Assign and access values
my_num = 5.7
print(my_num)
- A variable is like a labeled box that can store a value. Later you can access the value by naming the box.
Change values
my_num = 5.7
my_num = 14
print(my_num)
- This will display 14, because the variable will keep the last value that was assigned.
Simple data types
num_siblings = 4 # An integer (int) can only have whole numbers
age = 22.5 # A float can have a decimal
name = "John Doe" # A string (str) can store text (letters, numbers, and symbols)
is_student = True # A boolean (bool) can store True or False
- There are different types of data, but you don't have to specify which type it is.
- Sometimes values are treated differently based on their type, for example 2 + 2 = 4, but "2" + "2" is "22".
Change data types (casting)
whole_age = int(age)
has_siblings = bool(num_siblings)
message = "I have " + str(num_siblings) + " siblings"
- Sometimes it is useful to change a data type of a variable so it can work with other data types properly.
- The variable itself isn't modified by casting.
- When you cast a float to an int, it rounds down because an integer can't store decimal values.
- When you cast a number to a bool, it will be False if 0, or True for any other number.
- When you add to a string with the '+' operator, you can only add other strings.
Challenge
Create variables to store a customer's name, item name, item cost (as a float), purchase quantity (as an integer), and transaction number. Then display text for a payment receipt that includes all of that information. It should look something like this:
John Doe has purchased 7 apples for $0.76 each. Transaction number: 12356. Thank you.
Completed