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))