Comparison Operators

Every decision in your future code — every if, every filter, every login check — begins with one of these six operators asking a True/False question.

The six questions

age = 20

print(age == 20)    # True   equal to
print(age != 18)    # True   not equal to
print(age > 18)     # True   greater than
print(age < 18)     # False  less than
print(age >= 20)    # True   greater than or equal
print(age <= 19)    # False  less than or equal

Each comparison returns a boolean — a value you can store, pass around, and print:

can_vote = age >= 18
print(can_vote)          # True
print(type(can_vote))    # <class 'bool'>

That’s a big deal: comparisons aren’t just for if statements — they produce values. You’ll store them, put them in variables, and sum them up later in the course.

The = vs == rule (final exam version)

score = 85          # assignment: score BECOMES 85
print(score == 85)  # comparison: ASKS if score equals 85 → True

Inside if statements, using = instead of == is a syntax error in Python (other languages silently allow it — Python protects you):

if score = 85:      # SyntaxError: invalid syntax. Did you mean '=='?

Read the error text — modern Python literally suggests the fix.

Chaining comparisons — a Python superpower

Math-class notation works directly:

age = 25
print(18 <= age <= 65)     # True — "between 18 and 65, inclusive"

# equivalent to the longer form:
print(age >= 18 and age <= 65)

0 < x < 100 reads exactly like math class — and it’s not a trick, it’s real Python. Use it; it’s cleaner.

Comparing strings

print("apple" == "apple")    # True
print("Apple" == "apple")    # False — case matters!
print("apple" < "banana")    # True — dictionary order
print("" == "")              # True

Two practical patterns:

# Case-insensitive check — normalize first
answer = input("Continue? (yes/no) ")
print(answer.lower() == "yes")

# Empty-string check
name = input("Name: ")
print(name == "")             # did they type nothing?

Comparing different types

print(5 == 5.0)      # True  — int and float compare by VALUE
print("5" == 5)      # False — string vs number: never equal
print("5" > 3)       # TypeError: '>' not supported between 'str' and 'int'

== between mismatched types is simply False (no crash). But <, > between incompatible types crash. If you hit that TypeError, something upstream gave you a string where you expected a number — convert it.

Comparing with None — the `is` habit

result = None

print(result == None)    # works, but...
print(result is None)    # ← the Pythonic way

Both work, but is None is the community standard for checking “is there no value?” You’ll meet is formally in the operators module’s identity lesson.

Common Errors & Fixes

SyntaxError with = inside if — use ==.
Comparison always False — string vs number, or case mismatch. Print both sides and their type()s.
TypeError: '>' not supported — incompatible types; convert before comparing.

✅ Checkpoint

What does 10 != 10 return? (False)
Write a chained check: is x between 1 and 10? (1 <= x <= 10)
"Yes" == "yes"? (False — normalize with .lower() first)
Which do you use to check for None? (is None)

Next: logical operators — combining your True/False values into real decisions.

Comparison Operators