Question

我根据我所在的类的骨架编写了以下代码，它基于类的概念。我编写了类并编写了main，但我不断得到同样的错误，类中的函数未定义，这是我的代码：

class Person:
    population = 0
    def __init__(self, name):
        self.name = name
        print ('Initializing' ,self.name)
        Person.population += 1
    def __del__(self):
        print (self.name,"says bye.")
        Person.population -= 1
        if Person.population == 0:
            print ('I was the last one.')
        else:
            print ('There is/are still',Person.population ,'person/persons left.')  
    def sayHi(self):
        print("Hi, my name is ",self.name)
    def howMany(self):
        #Prints the current population.
        print(Person.population)
        #If there is only 1 person then it should print "I am the only one"
        if Person.population == 1:
            print("I am the only one")
            #If there are 2 people for example , then print "We have 2 people here"
        if Person.population == 2:
            print("We have 2 people here")
def main():

  # Step 1: Ask for names of 2 people
  x=input("name of person one?")
  y=input("name of person two?") 
  # Step 2: Initialize Person 1
  init1=__init__(x)
  # Step 3: Use function sayHi() for Person 1
  init1.sayHi()
  # Step 4: Use howMany() for Person 1
  init1.howMany()
  # Step 5: Initialize Person 2
  init2=__init__(y)
  # Step 6: Use function sayHi() for Person 2
  init2.sayHi()
  # Step 7: Use howMany() for Person 2
  init2.howMany()
  # Step 8: Say Hi to Person 1
  # Step 9: Use howMany() for Person 1
  init1.howMany()
  # Step 10: Terminate Person 1
  init1.__del__()
  # Step 11: Terminate Person 2
  init2.__del__()

main()

它不断产生错误NameError: name __init__ is not defined任何人都可以告诉我为什么会发生错误吗？

Answer 1

class Person:
 population = 0
 def __init__(self, name):
    self.name = name
    print ('Initializing' ,self.name)
    Person.population += 1
 def __del__(self):
    print (self.name,"says bye.")
    Person.population -= 1
    if Person.population == 0:
        print ('I was the last one.')
    else:
        print ('There is/are still',Person.population ,'person/persons left.')  
 def sayHi(self):
    print("Hi, my name is ",self.name)
 def howMany(self):
    #Prints the current population.
    print(Person.population)
    #If there is only 1 person then it should print "I am the only one"
    if Person.population == 1:
        print("I am the only one")
            #If there are 2 people for example , then print "We have 2 people here"
    if Person.population == 2:
        print("We have 2 people here")
def main():

  # Step 1: Ask for names of 2 people
  x=input("name of person one?")
  y=input("name of person two?") 
  # Step 2: Initialize Person 1
  init1= Person(x)
  # Step 3: Use function sayHi() for Person 1
  init1.sayHi()
  # Step 4: Use howMany() for Person 1
  init1.howMany()
  # Step 5: Initialize Person 2
  init2= Person(y)
  # Step 6: Use function sayHi() for Person 2
  init2.sayHi()
  # Step 7: Use howMany() for Person 2
  init2.howMany()
  # Step 8: Say Hi to Person 1
  # Step 9: Use howMany() for Person 1
  init1.howMany()
  init1 = None
  init2 = None

main()

Answer 2

__init__在您的课程中定义。因此，您可以在课堂外拨打__init__这样的功能main。

Answer 3

您正试图将__init__称为全局函数。这是Person的一种方法。尽管如此，您无需明确地致电__init__。

你可以打电话。

init1 = Person(x)

此外，您也无需明确致电__del__。当对象被垃圾收集时（在脚本的末尾），它将被自动调用。因此，您只需移除对__del__

的来电即可

用main编写一个python类

3 个答案: