练习 4.1
1. 判断题
判断下列描述的对错。
(1)子类是父类的子集。 ( ✖ )
(2)父类中非私密的方法能够被子类覆盖。 ( ✔ )
(3)子类能够覆盖父类的私密方法。 ( ✖ )
(4)子类能够覆盖父类的初始化方法。 ( ✔ )
(5)当创建一个类的实例时,该类的父类的初始化方法会被自动调用。 ( ✔ )
(6)所有的对象都是object类的实例。 ( ✔ )
(7)如果一个类没有显式地继承自某个父类,则就默认它继承自object类。 ( ✔ )
2. 代码分析题
(1)
class Parent(object):
x = 1
class Child1(Parent):
pass
class Child2(Parent):
pass
print (Parent.x, Child1.x, Child2.x)
Child1.x = 2
print (Parent.x, Child1.x, Child2.x)
Parent.x = 3
print (Parent.x, Child1.x, Child2.x)
1 1 1
1 2 1
3 2 3
(2)
class FooParent(object):
def __init__(self):
self.parent = 'I\'m the parent.'
print ('Parent')
def bar(self,message):
print( message,'from Parent')
class FooChild(FooParent):
def __init__(self):
super(FooChild,self).__init__()
print ('Child')
def bar(self,message):
super(FooChild, self).bar(message)
print ('Child bar fuction')
print (self.parent)
if __name__ == '__main__':
fooChild = FooChild()
fooChild.bar('HelloWorld')
Parent
Child
HelloWorld from Parent
Child bar fuction
I'm the parent.
(3)
class A(object):
def tell(self):
print('A tell')
self.say()
def say(self):
print('A say')
self.__work()
def __work(self):
print('A work')
class B(A):
def tell(self):
print('\tB tell')
self.say()
super(B, self).say()
A.say(self)
def say(self):
print('\tB say')
self.__work()
def __work(self):
print('\tB work')
self.__run()
def __run(self): # private
print('\tB run')
b = B();b.tell()
B tell
B say
B work
B run
A say
A work
A say
A work
3. 程序设计题
(1)编写一个类,由int类型派生,并且可以把任何对象转换为数字进行四则运算。
(2)编写一个方法,当访问一个不存在的属性时,会提示“该属性不存在”,但不停止程序运行。
(3)为学校人事部门设计一个简单的人事管理程序,满足如下管理要求。
① 学校人员分为三类:教师、学生、职员。
② 三类人员的共同属性是姓名、性别、年龄、部门。
③ 教师的特别属性是职称、主讲课程。
④ 学生的特别属性是专业、入学日期。
⑤ 职员的特别属性是部门、工资。
⑥ 程序可以统计学校总人数和各类人员的人数,并随着新人进入注册和离校注销而动态变化。
class Person:
def __init__(self, name, gender, age, department):
self.name = name
self.gender = gender
self.age = age
self.department = department
class Teacher(Person):
def __init__(self, name, gender, age, department=None, title=None, main_course=None):
super().__init__(name, gender, age, department)
self.title = title
self.main_course = main_course
class Student(Person):
def __init__(self, name, gender, age, department=None, major=None, enrollment_date=None):
super().__init__(name, gender, age, department)
self.major = major
self.enrollment_date = enrollment_date
class Employee(Person):
def __init__(self, name, gender, age, department=None, salary=None):
super().__init__(name, gender, age, department)
self.salary = salary
# 人员列表,用于存储所有人员信息
people = []
# 添加新人员函数
def add_person(person_type, name, gender, age, department):
if person_type == 'teacher':
people.append(Teacher(name, gender, age, department))
elif person_type == 'student':
people.append(Student(name, gender, age, department))
elif person_type == 'employee':
people.append(Employee(name, gender, age, department))
else:
print("Invalid person type.")
return
print(f"{person_type} {name} added successfully.")
print(f"Total {person_type}s: {len([p for p in people if isinstance(p, person_type)])}")
print("Total people: ", len(people))
# 统计各类人员数量的函数
def count_people():
total_teachers = len([p for p in people if isinstance(p, Teacher)])
total_students = len([p for p in people if isinstance(p, Student)])
total_employees = len([p for p in people if isinstance(p, Employee)])
print(f"Total teachers: {total_teachers}")
print(f"Total students: {total_students}")
print(f"Total employees: {total_employees}")
print(f"Total people: {len(people)}")
(4)为交管部门设计一个机动车辆管理程序,功能包括如下要求。
① 车辆类型(大客、大货、小客、小货、摩托)、生产日期、牌照号、办证日期。
② 车主姓名、年龄、性别、住址、身份证号。