Understanding Python's id(): Memory Addresses and Object Identity

Understanding Python's id(): Memory Addresses and Object Identity 🧠

The id() function in Python reveals an object's memory address (or unique identity). It's especially useful when comparing object references, debugging, or understanding how Python stores data in memory.

✅ Immutable objects: shared memory

# Immutable integers: same value = same object
a = 100
b = 100
print(id(a), id(b))       # same ID
print(a is b)             # True
print(a == b)             # True

✅ Mutable objects: separate memory

# Mutable lists: same content ≠ same object
x = [1, 2, 3]
y = [1, 2, 3]
print(id(x), id(y))       # different IDs
print(x is y)             # False
print(x == y)             # True

✅ Reference assignment: same ID

# Variable reference copy
z = x
print(id(x), id(z))       # same ID
print(x is z)             # True

✅ Tracking identity inside functions

# Tracking memory with id() inside a function
def trace_obj(obj):
    print(f"ID: {id(obj)}, VALUE: {obj}")

trace_obj(x)
trace_obj(y)

Using id() helps you distinguish between "same value" and "same object". In Python, knowing whether you're dealing with a copy or a reference can save you from unexpected behavior.

Value is not identity. Use id() to see beneath the surface and trace your objects like a pro. 🚀

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