Nested if Statements

Nested if Statements

An if statement can sit inside another one. The inner decision is only reached when the outer condition is True. Each level is indented one step further.

a, b, c = 5, 5, 8
if a + b > c and b + c > a and a + c > b:
    if a == b == c:
        print("Equilateral")
    elif a == b or b == c or a == c:
        print("Isosceles")
    else:
        print("Scalene")
else:
    print("Not a triangle")

The outer test checks that the three sides can form a triangle at all (each pair of sides must be longer than the third). Only then does the inner test decide its type. Python allows the chained comparison a == b == c, which means a == b and b == c.

Deep nesting is hard to read. When the branches do not depend on each other, a flat if/elif chain with and/or is usually clearer.

age, has_id = input().split()
age = int(age)
if age >= 18:
    print("Can vote")  # check has_id here with an inner if
else:
    print("Too young")