在Python中 - while循环不起作用，它导致在输入无效选项后不断打印else语句

Question

我正在学习Python并尝试使用while循环，但是如果输入无效的tip_val，则会连续获得else打印语句

def tip():
        print("Welcome to the tip calculator")
        bill = float(input("what is the total bill :"))
        ppl = int(input("how mny people spilt the bill :"))
        tip_val = int(input("what percentage of tip you would like to give i.e 10 or 12 or 15 :"))

        while True:
            if tip_val in (10, 12, 15):
                break
            else:
                print("invalid choice,please enter the valid discount from 10/12/15 ")
    
        disc_amount = (tip_val * bill) / 100
        total_amount = disc_amount + bill
        amount_per_prsn = total_amount / ppl
        print(f"discount amount is :{disc_amount}")
        print(f"total amount is :{total_amount}")
        print(f"each person got :{amount_per_prsn}")

tip()

Answer 1

您需要在循环中内部重新定义值，否则它只是一遍又一遍地检查相同的值：

def tip():
    print("Welcome to the tip calculator")
    bill = float(input("what is the total bill :"))
    ppl = int(input("how mny people spilt the bill :"))

    # move the tip calculation down here
    while True:
        tip_val = int(input("what percentage of tip you would like to give i.e 10 or 12 or 15 :"))

        if tip_val in (10, 12, 15):
            break
    
        print("invalid choice,please enter the valid discount from 10/12/15 ")

    disc_amount = (tip_val * bill) / 100
    total_amount = disc_amount + bill
    amount_per_prsn = total_amount / ppl
    print(f"discount amount is :{disc_amount}")
    print(f"total amount is :{total_amount}")
    print(f"each person got :{amount_per_prsn}")