类

类的实例方法

实例方法的第一个参数必须是”self”。
实例方法只能通过类实例进行调用，这时候”self”就代表这个类实例本身。通过”self”可以直接访问实例的属性，有了init方法，在创建实例的时候，就不能传入空的参数了，必须传入与init方法匹配的参数，但self不需要传。

class A(object):
    # 类的初始化
    def __init__(self, name):
        self.name = name
        print("init class A")
    def hello(self):
        print("hello {0}".format(self.name))

a = A("shan")
a.hello()

# 输出
init class A
hello shan

继承

继承
在Python中，同时支持单继承与多继承，实现继承之后，子类将继承父类的属性。

一般语法如下：

class SubClassName(ParentClass1 [, ParentClass2, ...]):
    class_suite

继承的例子

class Animal(object):
    def __init__(self, name):
        print("你现在正在初始化一个Animal")
    def run(self):
        print("Animal can run.")

class Bird(Animal):   #继承Animal
    def __init__(self):
        print("bird")
    def fly(self):
        print("Bird can fly.")

class Cat(Animal):   #继承Animal
    def __init__(self, name, sex):
        self.name = name
        self.sex = sex
        super(Cat, self).__init__(self.name)
        print("我是一只猫，啦啦啦啦")
    def jiao(self):
        print("miao miao miao miao")
    def run(self):
        print("我是一只猫，会上树来会跑路.")


class BianYi(Cat, Bird):   #继承Cat,Bird
    pass

cat = Cat("mao", "man")

# 输出
你现在正在初始化一个Animal
我是一只猫，啦啦啦啦

类中的调用方法

class DbArgs(object):
    # 只有类本身才可以调用
    __host = str("1.1.1.1")
    __port = str()
    __username = str()
    __password = str()
    __dbname = str()

    # 任何人可以调用
    name = "ajing"

    # 只能实例自己调用
    _host = "asdlfjasdl"
    def getHost(self):
        return self.__host

    def setHost(self, host):
        self.__host = host

dbArgs = DbArgs()
print(dbArgs.getHost())
dbArgs.name = "就是要改你，怎么的"
print(dbArgs.name)
print(dbArgs._host)

# 输出
1.1.1.1
就是要改你，怎么的
asdlfjasdl

类的应用例子

本实例主要是结合类的初始化，实例化，也使用了之前学的打开文件和写文件。

import codecs


class Student(object):
    def __init__(self, id, name, score):   #初始化 id，name，score
        self.id = id
        self.name = name
        self.score = score



class InitStduents():    
    def __init__(self):   # 初始化中定义一个list，执行init方法，init方法中添加list数据
        self.students = list()
        self.init()
    def init(self):
        self.students.append(Student(1001, "aaa", 59))
        self.students.append(Student(1002, "bbb", 96))
        self.students.append(Student(1003, "ccc", 87))
        self.students.append(Student(1004, "ddd", 89))
        self.students.append(Student(1005, "eee", 33))
        self.students.append(Student(1006, "fff", 85))
        self.students.append(Student(1007, "ggg", 78))
        self.students.append(Student(1008, "hhh", 97))
        self.students.append(Student(1009, "iii", 31))
        self.students.append(Student(1010, "jjj", 93))

    def sort(self):   # 类中的sort方法(list的排序)
        return sorted(self.students, key=lambda student: student.score)

    def writeFile(self, newStudents):   # 类中writeFile方法(把内容写进文件)
        with codecs.open("sortStudent.txt", "w")as f:
            for i in newStudents:
                f.write("id = {0}".format(i.id))
                f.write("\t")
                f.write("name = {0}".format(i.name))
                f.write("\t")
                f.write("score = {0}".format(i.score))
                f.write("\n")


def main():
    students = InitStduents()
    newStudents = students.sort()
    students.writeFile(newStudents)


if __name__ == "__main__":
    main()

# 查看newStudents
id = 1009   name = iii  score = 31
id = 1005   name = eee  score = 33
id = 1001   name = aaa  score = 59
id = 1007   name = ggg  score = 78
id = 1006   name = fff  score = 85
id = 1003   name = ccc  score = 87
id = 1004   name = ddd  score = 89
id = 1010   name = jjj  score = 93
id = 1002   name = bbb  score = 96
id = 1008   name = hhh  score = 97

使用类的方法编写之前的求阶乘和

class JinCinCount(object):
    def __init__(self, n):
        self.n = n
    def jc(self, n):
        result = 1
        if n == 0:
            return result
        else:
            for i in range(1, n+1):
                result *= i
            return result
    def count(self):
        count = 0
        for i in range(0, int(self.n) + 1):
            count += self.jc(i)
        print("count = {0}".format(count))

def main():
    n = input("Please inpurt a number: ")
    jinCinCount = JinCinCount(int(n))
    jinCinCount.count()

if __name__ == "__main__":
    main()

# 输出
Please inpurt a number: 5
count = 154