Variables and Types — PythonLessonLab

THE IDEA

Understand the concept

A variable is a name that refers to a value. Assign a value with =, then use the name in later expressions. Python determines the type from the value you assign.

Beginners commonly use integers, floating-point numbers, strings, and booleans. Use type() to inspect a value, and int(), float(), or str() when an explicit conversion is needed.

Assignment uses =
int, float, str, and bool
Convert types explicitly

WORKED EXAMPLES

See it step by step

Read the code, predict the output, then compare it with the result.

01. Store and display values

PYTHON

learner = "Sam"
completed = 4
print(learner, completed)

EXPECTED OUTPUT

Sam 4

Assignment gives the values names. print() can display two values separated by a space.

02. Inspect two types

PYTHON

score = 8.5
ready = True
print(type(score).__name__)
print(type(ready).__name__)

EXPECTED OUTPUT

float
bool

A decimal value is a float; True is a bool. type(...).__name__ shows each type's name.

HANDS-ON

Try it in Python

Edit the example and run it. Python starts in your browser the first time you click Run.

Python console

Ready to run

learner = "Maya"
lessons_finished = 3
progress = 0.5
is_learning = True
print(learner, lessons_finished)
print(type(progress).__name__)
print(type(is_learning).__name__)

Need input()? Add one value per line

Input lines

Ctrl / ⌘ + Enter to run

OUTPUT

Your output appears here.

Your turnCreate a variable named next_lesson with the number 4. Print a sentence that includes the learner's name and that number.

Need a hint?

Assign next_lesson = 4. Then print a line that uses both learner and next_lesson; print(learner, 'starts lesson', next_lesson) is one valid shape.

Complete the task and select Check task to verify your code.

KNOWLEDGE CHECK

Quick quiz

Three questions. You can change your answers and try again.

DEBUG BETTER

Typical mistakes

Everyone meets these errors. See what causes them and how to fix them.

Case-sensitive names

COMMON MISTAKE

name = "Maya"
print(Name)

FIX

name = "Maya"
print(name)

What happens: NameError because Name and name are different names.
Use exactly the same spelling and capitalization each time.

Mixing text and numbers