Day 27: Comparing floats directly

 

🐍 Python Mistakes Everyone Makes ❌

Day 27: Comparing Floats Directly

Floating-point numbers can look simple, but comparing them directly is one of the most common Python mistakes—especially for beginners.

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❌ The Mistake

a = 0.1 + 0.2
print(a == 0.3) # False 😨

Even though the math looks correct, the comparison fails.

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✅ The Correct Way

import math

a = 0.1 + 0.2 
print(math.isclose(a, 0.3)) # True ✅

❌ Why This Fails?

• Floats are stored in binary, not decimal

• Some decimal numbers cannot be represented exactly

• Small precision errors are introduced

• Direct equality (==) checks exact matches

• Results can be unexpected and buggy

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🧠 Simple Rule to Remember

✔ Never compare floats using ==
✔ Use math.isclose() or a tolerance
✔ Think approximate, not exact

Comparing floats safely makes your code more reliable, accurate, and professional 🚀