关于python：UnboundLocalError：赋值前引用的局部变量’cars’

UnboundLocalError: local variable 'cars' referenced before assignment

我正在制作一个程序，通过菜单存储和显示汽车的库存。但是，我不断地收到错误：

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".py", line 24, in car_invent
cars = cars.Car(make, model, mileage, price, doors)
UnboundLocalError: local variable 'cars' referenced before assignment"

我已经从一开始就导入了这个模块，我不明白它为什么会给我这个错误。

我的代码是

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import cars

def print_desc(item):
print"Make:", item.get_make()
print"Model:", item.get_model()
print"Mileage:", item.get_mileage()
print"Price:", item.get_price()

def car_invent():
car_invent = []

print"Enter data for the cars."

num_cars = input("Enter number of cars:")

for count in range(num_cars):
make = raw_input("Enter the make:")
model = input("Enter the year model:")
mileage = input("Enter the mileage:")
price = input("Enter the price:")
doors = input("Enter the number of doors:")

cars = cars.Car(make, model, mileage, price, doors)

car_invent.append(cars)

return car_invent

def truck_invent():
truck_invent = []

print"Enter data for the trucks."

num_trucks = input("Enter number of trucks:")

for count in range(num_trucks):
make = raw_input("Enter the make:")
model = input("Enter the year model:")
mileage = input("Enter the mileage:")
price = input("Enter the price:")
drive_type = input("Enter the drive type:")

trucks = cars.Truck(make, model, mileage, price, drive_type)

truck_invent.append(truck)

return truck_invent

def suv_invent():
suv_invent = []

print"Enter data for the cars."

num_suv = input("Enter number of SUVs:")

for count in range(1, num_suv):
make = raw_input("Enter the make:")
model = input("Enter the year model:")
mileage = input("Enter the mileage:")
price = input("Enter the price:")
pass_cap = input("Enter passenger capacity:")

suv = cars.SUV(make, model, mileage, price, pass_cap)

suv_invent.append(suv)

return suv_invent

def read_invent(car_invent, truck_invent, suv_invent):
print"USED CAR INVENTORY"
print"=================="
print"The following car is in inventory."

for item in car_invent:
print_desc(item)
print"Number of doors:", item.get_doors()

print"The following pickup truck is in inventory."

for item in truck_invent:
print_desc(item)
print"Drive type:", item.get_drive_type()

print"The following SUV is in inventory."

for item in suv_invent:
print_desc(item)
print"Passenger Capacity:", item.get_pass_cap()

def menu():
print"MENU"
print"====="
print"1. Enter data for inventory"
print"2. Display inventory"
print"3. Quit"

def main():
menu()

choice = input("Enter choice:")
while choice != 3:

if choice == 1:
cars = car_invent()
trucks = truck_invent()
suv = suv_invent()
choice = input("Enter choice:")

elif choice == 2:
read_invent(cars, trucks, suv)
choice = input("Enter choice:")

else:
print"Invalid choice"
choice = input("Enter choice:")

main()

以下是供参考的模块：

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class Automobile:

def __init__(self, make, model, mileage, price):
self.__make = make
self.__model = model
self.__mileage = mileage
self.__price = price

def set_make(self, make):
self.__make = make

def set_model(self, model):
self.__model = model

def set_mileage(self, mileage):
self.__mileage = mileage

def set_price(self, price):
self.__price = price

def get_make(self):
return self.__make
def get_model(self):
return self.__model

def get_mileage(self):
return self.__mileage
def get_price(self):
return self.__price

class Car(Automobile):
def __init__(self, make, model, mileage, price, doors):
Automobile.__init__(self, make, model, mileage, price)

self.__doors = doors

def set_doors(self, doors):
self.__doors = doors

def get_doors(self):
return self.__doors

class Truck(Automobile):
def __init__(self, make, model, mileage, price, drive_type):
Automobile.__init__(self, make, model, mileage, price)

self.__drive_type = drive_type

def set_drive_type(self, drive_type):
self.__drive_type = drive_type

def get_drive_type(self):
return self.__drive_type

class SUV(Automobile):
def __init__(self, make, model, mileage, price, pass_cap):
Automobile.__init__(self, make, model, mileage, price)

self.__pass_cap = pass_cap

def set_pass_cap(self, pass_cap):
self.__pass_cap = pass_cap

def get_pass_cap(self):
return self.__pass_cap

1	cars = cars.Car(make, model, mileage, price, doors)

声明一个名为cars的局部变量

您将cars.Car(...)分配给cars。

但是cars是一个局部变量，它还没有值(未绑定的局部变量)。

你的程序死机了