Python-TypeError：+不支持的操作數類型：“ int”和“ NoneType”

Question

這是我的第一門編程課，我很難解決這個問題。 我似乎無法使它正常工作，我不斷收到“ TypeError：+不支持的操作數類型：'int'和'NoneType”

def woodtype(wood):
    MAH=float(75.00)
    OAK=float(100)
    coffetab=float(0)
if woodtype=="mahogany":
    coffetab=MAH
else:
    if woodtype=="oak":
        coffetab=OAK


lamp=65
tables=155
print("the cost per desk lamp is $%.2f" %lamp)
print("the cost per coffee table is $%.2f" %tables)
dl=input("how many desk lamps are you buying?:")
desklamps=int(dl)
cf=input("how many coffee tables are you buying?:")
coffeetables=int(cf)
print("what type of wood would you like the coffee tables; mahogany, oak or pine.")
wood=input("what type of wood for your coffee tables?:")
costofwood=woodtype(wood)
total= (desklamps*65)+(coffeetables*(15+costofwood))
print("the total cost of your purchase is $%.2f" %total)

Answer 1

您的函數woodtype似乎縮進得很差，並且沒有return語句，因此它返回None 。

通過添加退貨，您應該能夠解決問題，例如

def woodtype(wood):
    MAH=float(75.00)
    OAK=float(100)
    coffetab=float(0)

    if wood=="mahogany":
        coffetab=MAH
    elif wood=="oak":
        coffetab=OAK

    return coffeetab