嵌套函数

# _*_ coding: utf-8 _*_
# 函数的嵌套调用：在一个函数内部有调用其他函数
# def max2(x,y):
#     if x > y:
#         return x
#     else:
#         return y
#
# def max4(a,b,c,d):
#     res1 = max2(a,b)
#     res2 = max2(res1,c)
#     res3 = max2(res2,d)
#
#     return res3
#
# print(max4(1,2,3,4))
# 4

# 函数的嵌套定义：在函数内又定义了其他函数
# def func():
#     def foo():
#         print('from foo')
#     print(foo)
#     # <function func.<locals>.foo at 0x10fe8bb70>
#     foo()
#     # from foo
#     x = 1
#     print(x)
#
# func()

# 通过嵌套定义函数求圆的周长或面积
# from math import pi
# def circle(radius,action): # 第一个参数输入半径，第二个参数控制输出的嵌套的函数
#     def cal_perimeter():
#         return 2*pi*radius
# 
#     def cal_area():
#         return pi * (radius**2)
# 
#     if action == 1: # 控制输出周长还是面积
#         res = cal_perimeter()
#     elif action == 2:
#         res=cal_area()
#     return res
# 
# res = circle(10,2)
# print(res)