Python：如何摆脱“无”

Question

def ask(x):
    while True:
        if x == "off":
            print("The cash register is closed")
            break
        elif x == "Bakery products":
            ask2 = float(input("Amount:"))
            print("Discount 30%. Amount due:", ask2 * 0.7) 
            continue
        elif x == "Dairy products":
            ask2 = float(input("Amount:"))
            print("Discount 10%. Amount due:", ask2 * 0.1) 
            continue
        else:
            ask4 = float(input("Amount:"))
            print("Amount due:", ask4)
while True:
    ask1 = input("Catergory (off - complete):")
    if ask1 == "off":
        print("The cash register is closed")
        break  

    elif ask1 == "Bakery products":
        ask2 = float(input("Amount:"))
        print("Discount 30%. Amount due:", ask2 * 0.7) 
        print(ask(input("Enter product category:")))
        break

    elif ask1 == "Dairy products":
        ask2 = float(input("Amount:"))
        print("Discount 10%. Amount due:", ask2 * 0.1)
        print(ask(input("Enter product category:")))
        break

    else:
        ask4 = float(input("Amount:"))
        print("Amount due:", ask4)
        print(ask(input("Enter product category:")))
        break

So, for this code above, at the end when I try to quit it by typing "off", but at the end there is not only "The cash register is closed" printed, but also "None" printed. Does anyone know how to get rid of "None"?

Answer 1

You already have print in the ask function, you don need it outside it.

def ask(x):
    while True:
        if x == "off":
            print("The cash register is closed")
            break
        elif x == "Bakery products":
            ask2 = float(input("Amount:"))
            print("Discount 30%. Amount due:", ask2 * 0.7) 
            continue
        elif x == "Dairy products":
            ask2 = float(input("Amount:"))
            print("Discount 10%. Amount due:", ask2 * 0.1) 
            continue
        else:
            ask4 = float(input("Amount:"))
            print("Amount due:", ask4)
while True:
    ask1 = input("Catergory (off - complete):")
    if ask1 == "off":
        print("The cash register is closed")
        break  

    elif ask1 == "Bakery products":
        ask2 = float(input("Amount:"))
        print("Discount 30%. Amount due:", ask2 * 0.7) 
        ask(input("Enter product category:"))
        break

    elif ask1 == "Dairy products":
        ask2 = float(input("Amount:"))
        print("Discount 10%. Amount due:", ask2 * 0.1)
        ask(input("Enter product category:"))
        break

    else:
        ask4 = float(input("Amount:"))
        print("Amount due:", ask4)
        ask(input("Enter product category:"))
        break