定义一个类：实现功能可以返回随机的10个数字，随机的10个字母， 随机的10个字母和数字的组合；字母和数字的范围可以指定，类似（1~100）（A~z）

#习题2：定义一个类：实现功能可以返回随机的10个数字，随机的10个字母，

#随机的10个字母和数字的组合；字母和数字的范围可以指定

class RandomString():

    #随机数选择的范围作为参数，如（1~100）字母 （'A'~'z'）,大写字母在前 按ascii值排列先后

    def __init__(self,start_num=0,end_num=100,start_alpha='A',end_alpha='z'):

        import string

        if not isinstance(start_num,int) or not isinstance(end_num,int) or \

        not isinstance(start_alpha,str) or not isinstance(end_alpha,str) or \

        (start_alpha not in string.ascii_letters or end_alpha not in string.ascii_letters):

            print('参数类型错误，请重新输入！')

            return None

        self.start_num=start_num

        self.end_num=end_num

        self.start_alpha=start_alpha

        self.end_alpha=end_alpha

    #生成要求数量随机数字,num 随机数的数量

    def random_digits(self,num):

        print('self.start_num,self.end_num:',self.start_num,self.end_num)

        if not isinstance(num,int):

            print('数字类型输入错误，请重新输入')

            return None

        from random import randint

        num_list=[]

        for i in range(num):

            num_list.append(randint(self.start_num,self.end_num))

        return num_list

    #生成要求数量随机字母，大小写混合

    def random_letters(self,num):

        if not isinstance(num,int):

            print('数字类型输入错误，请重新输入')

            return None

        from random import randint

        import string

        all_letters=string.ascii_uppercase+string.ascii_lowercase

        start_position=all_letters.find(self.start_alpha)

        end_position=all_letters.find(self.end_alpha)

        if start_position>end_position:

            start_position,end_position=end_position,start_position

        letters_list=[]

        for i in range(num):

            letters_list.append(string.ascii_letters[randint(start_position,end_position)])

        return letters_list

    def random_digits_letters(self,num):

        digits_string=list(range(self.start_num,self.end_num+1))

        print('digits_string',digits_string)

        import string

        all_letters=string.ascii_uppercase+string.ascii_lowercase

        print('all_letters',all_letters)

        print('self.start_alpha',self.start_alpha)

        print('self.end_alpha',self.end_alpha)

        start_position=all_letters.find(self.start_alpha)

        end_position=all_letters.find(self.end_alpha)

        letters_string=list(all_letters[start_position:end_position+1])

        print('letters_string',letters_string)

        from random import choice

        all_string=digits_string+letters_string

        print('all_string',all_string)

        all_list=[]

        for i in range(num):

            all_list.append(choice(all_string))

        return all_list

randomdigitalpha=RandomString(2,100,'W','e') #

print(randomdigitalpha.start_num)

print(randomdigitalpha.random_digits(10))

print(randomdigitalpha.random_letters(5))

print(randomdigitalpha.random_digits_letters(15))