bool Comparisons¶

Comparisons test relationships between values and produce Boolean results.

These results are central to decision making in Python.

Common comparison operators include:

flowchart TD
    A[Two values] --> B[comparison operator]
    B --> C[Boolean result]
````

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## 1. Equality and Inequality

Equality checks whether two values are the same.

```python
print(5 == 5)
print(5 != 3)

Output:

True
True

These comparisons work across many types.

print("a" == "a")
print([1, 2] == [1, 2])

2. Ordering Comparisons¶

Ordering operators compare relative size.

print(3 < 5)
print(10 > 7)
print(4 <= 4)
print(8 >= 10)

Output:

True
True
True
False

These are especially common in loops and conditions.

3. Chained Comparisons¶

Python supports chained comparisons.

x = 7
print(0 < x < 10)

Output:

True

This is equivalent to:

print(0 < x and x < 10)

but is often more readable.

4. Comparing Different Types¶

Some comparisons between unlike types are allowed, while others are not.

print(3 == 3.0)

Output:

True

But ordering unrelated types may fail.

# "3" < 4   # TypeError

Python does not impose arbitrary ordering across unrelated types.

5. Identity vs Equality¶

Python distinguishes equality from identity.

a = [1, 2]
b = [1, 2]

print(a == b)
print(a is b)

Output:

True
False

• == checks whether values are equal
• is checks whether two names refer to the same object

This distinction is especially important with None.

6. Membership Comparisons¶

Python also provides membership tests.

Example:

print("a" in "cat")
print(5 in [1, 2, 5])

Output:

True
True

7. Worked Examples¶

Example 1: password check¶

password = "secret"

print(password == "secret")

Output:

True

Example 2: numeric range¶

score = 82

if 80 <= score < 90:
    print("B range")

Example 3: membership¶

colors = ["red", "green", "blue"]

if "green" in colors:
    print("found")

8. Common Pitfalls¶

Using is instead of ==¶

For value comparison, use ==, not is.

Comparing unrelated types with ordering operators¶

Expressions like "10" < 20 are invalid.

9. Summary¶

Key ideas:

• comparisons produce Boolean results
• equality and ordering comparisons are fundamental to control flow
• chained comparisons improve readability
• == and is have different meanings
• membership tests also produce Boolean values

Comparison operators allow Python programs to reason about relationships between values.