Conditionals (if / else)

Conditionals run code only when a condition is true.

age = 18

if age >= 18:
    print("adult")

else

if age >= 18:
    print("adult")
else:
    print("minor")

elif

For several conditions in sequence:

grade = 7

if grade >= 9:
    print("excellent")
elif grade >= 6:
    print("passed")
else:
    print("failed")

Indentation defines the block

What’s indented after the if belongs to it:

if age >= 18:
    print("line 1")
    print("line 2")   # also runs only if adult
print("always runs")

One-line if (ternary)

status = "adult" if age >= 18 else "minor"

Combined conditions

if age >= 18 and age < 65:
    print("working age")