String Formatting & None

f-strings are the modern default: f"{name} scored {score}". .format() and % formatting still appear in older code.

Python String Formatting

f-strings are the modern default: f"{name} scored {score}". .format() and % formatting still appear in older code.

Format numbers: f"{price:.2f}", f"{n:,}" for thousands separators.

Real-life example: String formatting is filling a form letter — same sentence, different names each time.

f-string formatting

name, score = "Riya", 92.567
print(f"{name} scored {score:.1f}%")
print("{} scored {:.1f}%".format(name, score))

None means no value or missing data. Functions without return implicitly return None.

Check with is None — not == None. Optional parameters often default to None.

Real-life example: None is an empty chair — the seat exists but nobody is sitting there yet.

None checks

result = None

def find_user(id):
    return None  # not found

user = find_user(99)
if user is None:
    print("User not found")