ApexDelight

Is vs == Python

• apexdelight
• March 10, 2025March 10, 2025
• 0

is vs == in Python

Python provides two different operators for comparison: is and ==. While they might seem similar, they serve distinct purposes.

1. == (Equality Operator)

The == operator checks if the values of two objects are equal. It does not care whether they are stored at the same memory location.

Example:

pythonCopyEditx = [1, 2, 3]
y = [1, 2, 3]
print(x == y)  # Output: True

Here, x and y have the same values, so == returns True, even though they are different objects in memory.

Key Points:

• Compares values.
• Works with numbers, strings, lists, dictionaries, etc.
• Returns True if the values are the same, regardless of memory location.

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2. is (Identity Operator)

The is operator checks whether two variables refer to the same object in memory.

Example:

pythonCopyEditx = [1, 2, 3]
y = [1, 2, 3]
print(x is y)  # Output: False

Even though x and y have the same values, they are stored separately in memory, so is returns False.

Key Points:

• Compares memory addresses, not values.
• Returns True only if both variables point to the exact same object.
• Often used for checking singleton objects like None, True, and False.

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3. Key Differences:

Feature	== (Equality)	is (Identity)
Compares	Values	Memory locations
Works on	Numbers, lists, strings, etc.	Objects, singletons (None, True, False)
Output	True if values match	True if both variables point to the same object

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4. Common Pitfalls

Using is Instead of ==

pythonCopyEditx = 1000
y = 1000
print(x is y)  # Output: False (Different memory locations)

For large integers, Python stores them separately, so is does not work.

Incorrect Use of == for None

pythonCopyEditx = None
if x == None:  # Avoid this
    print("Incorrect way to check for None")

✅ Correct approach:

pythonCopyEditif x is None:
    print("Correct way to check for None")

Use is for None comparisons, as per Python’s best practices.

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5. When to Use is vs ==

• ✅ Use == when checking if values are equal.
• ✅ Use is when checking if two variables refer to the same object.
• ✅ Prefer is for checking None, True, or False.

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6. Conclusion

• == checks for value equality.
• is checks for object identity (same memory location).
• Misusing them can lead to subtle bugs, so understanding their difference is crucial in Python programming.