Python披萨计价代码问题：S尺寸披萨加芝士未计入总价

问题现象 #

选择S尺寸披萨且仅添加额外芝士时，芝士的1美元费用未计入最终总价，但M/L尺寸的功能看似正常。

终端测试输出 #

Welcome to Python Pizza Deliveries!
What size pizza do you want? S, M, or L S
Do you want pepperoni? Y or N N
Do you want extra cheese? Y or N Y
Your final bill is: $15.

原代码 #

print("Welcome to Python Pizza Deliveries!")
size = input("What size pizza do you want? S, M, or L ")
add_pepperoni = input("Do you want pepperoni? Y or N ")
extra_cheese = input("Do you want extra cheese? Y or N ")
price = 0
if size == "L":
    price = 25
    if add_pepperoni == "Y":
        price += 3
        if extra_cheese == "Y":
            price += 1
if size == "M":
    price = 20
    if add_pepperoni == "Y":
        price += 3
        if extra_cheese == "Y":
            price += 1
if size == "S":
    price = 15
    if add_pepperoni == "Y":
        price += 2
        if extra_cheese == "Y":
            price += 1
print(f"Your final bill is: ${price}.")

错误原因 #

所有尺寸的extra_cheese判断都嵌套在了add_pepperoni == "Y"的分支内部，这意味着只有选择添加pepperoni时，才会检查是否添加额外芝士。你测试S尺寸时没选pepperoni，所以芝士加价的代码根本没机会执行。M/L尺寸其实也存在同样的逻辑漏洞，只是你没测试「不加pepperoni只加芝士」的场景而已。

修复后的代码 #

把芝士加价的判断从pepperoni的分支里提出来，放在对应尺寸的代码块中，和pepperoni的判断同级：

print("Welcome to Python Pizza Deliveries!")
size = input("What size pizza do you want? S, M, or L ")
add_pepperoni = input("Do you want pepperoni? Y or N ")
extra_cheese = input("Do you want extra cheese? Y or N ")
price = 0
if size == "L":
    price = 25
    if add_pepperoni == "Y":
        price += 3
    if extra_cheese == "Y":
        price += 1
if size == "M":
    price = 20
    if add_pepperoni == "Y":
        price += 3
    if extra_cheese == "Y":
        price += 1
if size == "S":
    price = 15
    if add_pepperoni == "Y":
        price += 2
    if extra_cheese == "Y":
        price += 1
print(f"Your final bill is: ${price}.")

内容的提问来源于stack exchange，提问作者Zo.A