🧠 Python Identity Operators (is, is not) – Explained with Examples

Python’s identity operators—is and is not—are often misunderstood by beginners. While they look similar to comparison operators, they behave differently by checking whether two variables point to the same memory location, not just equivalent values.

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🔍 What Are Identity Operators in Python?

Identity operators compare the memory location of two objects, not their values. They are:

🔑 Operator	🧠 Description
is	Returns True if both variables refer to the same object (i.e., same memory address).
is not	Returns True if they do not refer to the same object.

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✅ Example 1 – Same Reference

a = [1, 2, 3]
b = a
print(a is b)      # ✅ True – both refer to the same object
print(a == b)      # ✅ True – values are also equal

✅ Explanation:

• a is b: ✔ True, because b points to the same list as a.
• a == b: ✔ True, because the list values are the same.

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⚠️ Example 2 – Different Objects with Same Content

x = [1, 2, 3]
y = [1, 2, 3]
print(x is y)      # ❌ False – different memory addresses
print(x == y)      # ✅ True – contents are equal

⚠️ Explanation:

• x is y: ❌ False because x and y are two different list objects.
• x == y: ✔ True because they have the same values.

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💡 Example 3 – Identity with Immutable Types

a = 100
b = 100
print(a is b)   # ✅ True (cached by Python for small integers)

a = 5000
b = 5000
print(a is b)   # ❌ False (not always cached)

💡 Tip:

• Python internally caches small integers and strings, so is might return True for those, but it should not be relied upon for comparisons.

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📘 Best Practices

• ✅ Use is and is not for:
  • Comparing with None (if x is None)
  • Checking if two variables refer to the same object (identity check)
• ⚠️ Do NOT use is for:
  • Value comparison (use == instead)

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📊 Comparison: is vs ==

Check Type	is	==
Compares	Memory location	Values
Returns True	If same object	If values are the same
Example	x is y	x == y
Use Case	if x is None:	if x == 0:

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❓FAQs

❓What is the difference between is and == in Python?

is checks identity (same memory location), while == checks equality (same value).

❓Should I use is to compare strings or numbers?

No. Use == for value comparisons. Python might cache small strings or numbers, but that’s not guaranteed across all Python implementations.

❓Why does None require is instead of ==?

Because None is a singleton in Python. Checking with is ensures you’re referring to the actual None object.

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🔚 Summary

• Use is / is not to check object identity.
• Use == / != to check value equality.
• Common in conditional checks involving None.

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✅ FAQ – Python Identity Operators

❓What are identity operators in Python?

Identity operators (is and is not) are used to check if two variables reference the same object in memory, not just if they have the same value.

❓What is the difference between is and == in Python?

• is checks whether two variables point to the same memory address.
• == checks if the values are equal, regardless of memory address.

❓When should I use is in Python?

Use is when you want to check identity, such as:

if x is None:

This ensures you’re comparing with the singleton None object.

❓Why does a is b return False even if a == b is True?

Because they might have the same value but are stored in different memory locations, especially with mutable data types like lists and dictionaries.

❓Is it safe to use is to compare strings and integers?

Only for small values. Python caches small integers and some strings, so is might work for those—but it’s not guaranteed. Always use == for value comparison.

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