1 python_name = {"alex","tom","jime","limei"}
 2 linux_name = {"alex","tom","zhangsan"}
 3 p_n = set(python_name)
 4 l_n = set(linux_name)
 5 #求交集
 6 print(p_n.intersection(l_n))
 7 print(p_n & l_n)
 8 #求并集
 9 print(p_n.union(l_n))
10 print(p_n | l_n)
11 #求差集
12 print(p_n.difference(l_n))
13 print(p_n-l_n)
14 #交叉补集
15 print(p_n.symmetric_difference(l_n))
16 print(p_n^l_n)

 1 #字符串格式化
 2 t = "i am %s " % "tom"
 3 print(t)
 4 #%s可以是任意值（字符串、数字，列表，元祖，字典） %d只可以接收数字
 5 t = "i am %s age %d " % ("tom",18)
 6 print(t)
 7 #浮点数（小数）%f 默认保留六位小数 %.2f保留2位小数  %.3s字符串截取操作
 8 t = 'percent %.2f ' % 99.942562
 9 print(t)
10 #打印百分比%%
11 t = 'percent %.2f %%' % 99.942562
12 print(t)
13 #%(name)s   %(age)d 键值  对应的传字典key对应的值
14 t = "i am %(name)s age %(age)d " % {"name":"alex","age":18}
15 print(t)

 1 python中函数定义方法：
 2
 3 def test(x):
 4     "The function definitions"
 5     x+=1
 6    return x
 7
 8 def:定义函数的关键字
 9 test：函数名
10 （）：内可定义形参
11 "":文档描述（非必要，但是强烈建议为你的函数添加描述信息）
12 x+=1：泛指代码块或程序处理逻辑
13 return：定义返回值

 1 #定义全局变量
 2 name = "tom"
 3 age =18
 4 def chang_name():
 5     global name,age #指定局部变量为全局变量
 6     age = 11
 7     name= "alex"   #局部变量
 8     print("chang_name",name,age)
 9 chang_name()      #变量参数
10 print(name,age)

#/函数之前的嵌套
NAME = "ALEX"
def tom():name = "zhangsan"print(name)def arm():  #嵌套函数name = "zhaosi"print(name)def li():       #嵌套函数name = "wangwu"print(name)print(name)li()arm()print(name)
tom()
print(NAME)

 1 name = "alex"
 2 def zhangsan():
 3     name = "zhangsan"
 4     def lisi():
 5         # global name #全局变量
 6         nonlocal name #上一级局部变量
 7         name = "lisi"
 8         return
 9     lisi()
10     print(name)
11 print(name)
12 zhangsan()
13 print(name)