Values, Objects, and Types

Unit ID: M02-U00 Estimated active time: 18-25 minutes

Why type matters

In Module 1, you used numbers and text. Now we will look more closely at what Python knows about each value.

Run:

print(type(25))
print(type(25.0))
print(type("25"))
print(type(True))
print(type(None))

You should see the types int, float, str, bool, and NoneType.

A value is a piece of information used by a program. In Python, values are objects. Every object has a type. The type helps determine which operations make sense.

Similar appearance, different meaning

These values look related but are different:

25
25.0
"25"

• 25 is an integer: a whole number.
• 25.0 is a floating-point number: a number represented with a decimal form.
• "25" is a string: text containing the characters 2 and 5.

Predict the results:

print(25 + 5)
print("25" + "5")

The first result is 30. The second is 255 because + joins the two strings. Python did not make a mathematical mistake. It followed the operation defined for each type.

Inspect rather than guess

Use type() when the type is unclear:

course_hours = "32"
print(type(course_hours))

The name contains the word hours, but the value is still text. A clear name helps people; it does not change the Python type.

Type is not the complete story

Knowing the type does not prove that a value is correct. -10 is an integer, but it may be invalid for a course duration. "unknown" is a string, but it may not be an approved course status.

Later modules will add validation rules. For now, separate two questions:

1. What type is this value?
2. Is this value suitable for the task?

Guided practice

Predict each type before running:

course_name = "Python Foundations for AI"
module_number = 2
estimated_hours = 3.5
is_available = False
instructor_name = None

print(type(course_name))
print(type(module_number))
print(type(estimated_hours))
print(type(is_available))
print(type(instructor_name))

Explain what each value represents in the fictional course record.

Takeaway

Every Python value has a type, and type affects what operations mean. Inspect with type() instead of trusting appearance or a variable name. Next, we will trace how names refer to values and what reassignment changes.