使用一个例子去理解CLASS，类的内容（2）

回到他的需求：

1，可以新增记录，2，可以查询，3，可以全部展示，4，可以删除，5，可以更新。

那么我们先把大框架搭起来：

class Contact(object):

    def __init__(self):
        pass

    def search_contact(self, args):
        pass

    def display_all(self):
        pass

    def update_number(self, new_number):
        pass

    def delete_contact(self):
        pass

 看，一个类，Contact，还有包括初始化在内的5个方法，已经涵盖了我们的要求了

然后搭好所有的类

别忘了：

1，你要在一个list里保存所有的信息，所以要定义在class中

2，search和display应该是classmethod

3，update应他要求，也做成了classmethod

class Contact(object):
    con = []

    def __init__(self):
        self.f = None
        self.l = None
        self.n = None
        self.a = None
        self.list = []

    def setup_ins(self):
        '''f as first name,l as last name,n as number,a,as address,con as all_contacts'''
        self.f = str(input('input first name:'))
        self.l = str(input('input last name:'))
        self.n = str(input('input number:'))
        self.a = str(input('input address:'))
        # print(self.f, self.l, self.n, self.a)
        if self.f == '' or self.l == '' or self.n == '' or self.a == '':
            return 0
        else:
            self.list.extend([self.f, self.l, self.n, self.a])
            Contact.con.append(self.list)

    @classmethod
    def search_contact(cls, args):
        if args == '':
            return 0
        else:
            for obj in Contact.con:  # first list
                if args in obj:  # searching in second list
                    print(obj)
                    return 1
                else:
                    print('no such a record!')

    @classmethod
    def display_all(cls):
        for obj in Contact.con:
            print(obj)

    @classmethod
    def update_number(cls, old_number, new_number):
        for obj in Contact.con:  # first list
            if old_number in obj:  # searching in second list
                i = Contact.con.index(obj)
                j = obj.index(old_number)
                Contact.con[i][j] = new_number
                return 1
            else:
                return 0

    def delete_contact(self):
        i = Contact.con.index(self.list)
        Contact.con.pop(i)

 下面是调用的部分：

while 1:
    print('<<<<<<<<<<<<<<<<<<<<<<make a choice>>>>>>>>>>>>>>>>>>>>>>>')
    print('<<<<<<<<<<<<<<<<<<<<<<(1)add record>>>>>>>>>>>>>>>>>>>>>>>')
    print('<<<<<<<<<<<<<<<<<<<<<<(2)search record>>>>>>>>>>>>>>>>>>>>>>>')
    print('<<<<<<<<<<<<<<<<<<<<<<(3)show all record>>>>>>>>>>>>>>>>>>>>>>>')
    print('<<<<<<<<<<<<<<<<<<<<<<(4)delete record>>>>>>>>>>>>>>>>>>>>>>>')
    print('<<<<<<<<<<<<<<<<<<<<<<(5)update record >>>>>>>>>>>>>>>>>>>>>>>')
    print('<<<<<<<<<<<<<<<<<<<<<<(6)exit >>>>>>>>>>>>>>>>>>>>>>>')
    choice = input('make your choice(1/2/3/4/5/6):')
    # print(type(choice))  # debug
    if choice == '1':
        user_name = str(input('type a user_name:'))
        res = 1
        exec('%s = Contact()' % user_name)
        exec('res = %s.setup_ins()' % user_name)
        if res == 0:
            print('error please completely input!')
            exec('del(%s)' % user_name)
        continue
        # Contact.display_all()  # debug
    elif choice == '2':
        search_obj = str(input('what do you want to search:'))
        res = Contact.search_contact(search_obj)
        if res == 0:
            print('input something!')
        continue

    elif choice == '3':
        Contact.display_all()
        continue

    elif choice == '4':
        delete_name = str(input('who do you want to delete:'))
        exec('%s.delete_contact()' % delete_name)
        continue

    elif choice == '5':
        old_num = str(input('type old number:'))
        new_num = str(input('type new number:'))
        res = Contact.update_number(old_num, new_num)
        if res == 1:
            print('success!')
        else:
            print('failed!')
        continue

    elif choice == '6':
        print('bye!')
        break
    else:
        print('wrong input! only 1,2,3,4,5 or 6!')
        continue

 代码都很简单，不做过多解释，重在理解class的概念