"""
练习判断一个小数
1、判断是否合法
2、合法需要有一个小数点
3、小数点左边必须是个整数，右边必须是个正整数

"""

def xiaoshu(s):
    xiaoshu_new=str(s)

    if xiaoshu_new.count(".") ==1:
       left,right = xiaoshu_new.split(".")
       if left.isdigit() and right.isdigit():
           print(1111)
           return True

       elif left.startswith('-') and left.count('-') == 1 and right.isdigit():
            lleft = left.split('-')[-1]
            if lleft.isdigit():
                return True

    return False


a = xiaoshu(-.1)

print(a)