id and type

Learn object identity and type with id() and type().

What is id?

Every object in Python has a unique identity. The id() function returns it:

x = 5
print(id(x))  # example: 140234567890

The identity is the address of the object in memory. Two objects with the same value may have different identities. But for small integers Python shares them (interning).

The is operator checks whether two variables point to the same object by identity.

type vs isinstance

type(x) returns the type object of the variable. isinstance(x, int) returns True/False whether x is of that type.

type(5) == int            # True
isinstance(5, int)        # True

isinstance also considers inheritance, so it is preferred for type checks. type is used when exact type equality is needed.

Exercise Print the type

Assign 5 to x. Then print its type with print(type(x)).

Show example solution

x = 5
print(type(x))

Test yourself

What does type(5) return?
- 5
- int
- <class 'int'>
- integer
Show answer

<class 'int'> — type(5) returns <class 'int'>.
Check the type
```
type(x) == ____
```
Show answer
```
type(x) == int
```
Match the concepts

id()

Object identity
type()

Type object
isinstance()

Inheritance-aware check
is

Identity comparison

Next lesson: Swapping variables

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