Activity 1.3

Variables and Data Types

Key Concepts

Storing Information

Variables and Data Types

What is a Variable?

A variable stores a value so your program can use it again later.

You Have Been Looking at Variables for Years

Score. High score. Health. Time. Every number on that bar is a value the game is storing and showing you.

Every Game Does This

• Score changes when you hit something
• Health changes when you get hit
• Lives changes when you die

The game has to keep those three numbers somewhere. That somewhere is a variable.

What is a Variable?

name = "Anthony"
age = 35

print(name)
print(age)

Anthony
35

Data Types

Python automatically figures out what type of data a variable holds.

• str — text, wrapped in quotes
• int — a whole number
• float — a decimal number

Data Types

Use the built-in type() function to check a variable's data type.

name = "Anthony"
age = 35
height = 5.9

print(type(name))
print(type(age))
print(type(height))

<class 'str'>
<class 'int'>
<class 'float'>

Naming Variables

• Use all lowercase letters
• Separate words with an underscore, like favorite_color
• Choose descriptive names
• Names cannot start with a number

Today's Objectives

• Declaring and assigning variables
• Displaying variable values
• Identifying data types with type()

Key Terms

Variable

A named location that stores a value for later use.

Assignment

Storing a value in a variable using the = operator.

Data Type

The kind of value a variable holds, such as text or a number.

String (str)

A data type representing text.

Integer (int)

A data type representing a whole number.

Float (float)

A data type representing a decimal number.

'F' → Fullscreen

Build

Create a new Python program named 1-3-variables.

Task 1: Declare Your Variables

• Create a name variable (a string) and an age variable (an integer).
• Print each variable on its own line.

1
name = "Anthony"
2
age = 35
3

4
print(name)
5
print(age)
6
#

Task 2: Add More Variables

• Create a favorite_color variable (a string) and a favorite_number variable (a float).
• Print each one using a label, e.g. print("Favorite Color:", favorite_color).
• Note: separating two values with a comma inside print() prints them on the same line with a space in between.

1
name = "Anthony"
2
age = 35
3

4
print(name)
5
print(age)
6

7
favorite_color = "green"
8
favorite_number = 7.5
9

10
print("Favorite Color:", favorite_color)
11
print("Favorite Number:", favorite_number)
12
#

Task 3: Check Your Data Types

• Use type() to print the data type of each of your four variables.

1
name = "Anthony"
2
age = 35
3

4
print(name)
5
print(age)
6

7
favorite_color = "green"
8
favorite_number = 7.5
9

10
print("Favorite Color:", favorite_color)
11
print("Favorite Number:", favorite_number)
12

13
print(type(name))
14
print(type(age))
15
print(type(favorite_color))
16
print(type(favorite_number))
17
#

Challenge (Optional): Reassign and Recheck

• Reassign one of your variables to a value of a different data type. For example, change age = 35 to age = "thirty-five".
• Print its data type again and compare the result.

Checkpoint

Verify your program works correctly.

Anthony
35
Favorite Color: green
Favorite Number: 7.5
<class 'str'>
<class 'int'>
<class 'str'>
<class 'float'>

Reflection

Answer the following questions before submitting your work.

1. What is a variable, and why are variables useful in a program?
2. Python does not require you to announce a variable's data type ahead of time — it figures the type out automatically. What do you think would happen if you tried to use a variable before assigning it a value?
3. If you completed the optional challenge, what did type() report after you reassigned a variable to a different data type?

Submit

Submit the required files to the appropriate dropbox.

Activity Complete