Mastering Common Nested if Statements in Python

Python allows the if statement to be nested arbitrarily, enabling single‑branch, double‑branch, or multi‑branch logic to be combined in any order.

Typical nested syntax looks like:

if expression1:
    if expression2:
        if expression3:
            execute_statement

The nesting can be mixed with elif and else clauses, but the core idea is that each inner if is evaluated only when the outer condition holds true.

Example scenario: a user is asked whether they have bought a ticket and whether they passed security. The code uses nested if statements to branch based on the answers.

ticket = input("是否买到了车票?")
if ticket == "yes":
    print("买到了车票,可以进站!")
    safe = input("安检是否通过?")
    if safe == "yes":
        print("安检过关,可以进入候车室")
    else:
        print("安检未通过,请检查携带物品")
else:
    print("车票都没有,走远点!")

When the user answers yes to the ticket question and no to the security check, the program outputs:

是否买到了车票？ yes
买到了车票，可以进站！
安检是否通过？ no
安检未通过，请检查携带物品。

This demonstrates how nested if statements control program flow based on sequential user inputs.