程序中可重复使用的程序段,给一段程程序起一个名字，用这个名字来执行一段程序，反复使用 （调用函数）
语法用关键字 ‘def' 来定义，identifier(参数),参数为list
局部变量 vs 全局变量#-*- coding: utf-8 -*-#没有参数和返回的函数def say_hi(): print(" hi!") say_hi() say_hi()#有参数，无返回值 def print_sum_two(a, b): c = a + b print(c) print_sum_two(3, 6) def hello_some(str): print("hello " + str + "!") hello_some("China") hello_some("Python")#有参数，有返回值 def repeat_str(str, times): repeated_strs = str * times return repeated_strs repeated_strings = repeat_str("Happy Birthday!", 4) print(repeated_strings)#全局变量与局部 变量 x = 60 def foo(x): print("x is: " + str(x)) x = 3 print("change local x to " + str(x)) foo(x) print('x is still', str(x)) 默认参数def repeat_str(s, times = 1): repeated_strs = s * times return repeated_strsrepeated_strings = repeat_str("Happy Birthday!")print(repeated_strings)repeated_strings_2 = repeat_str("Happy Birthday!" , 4)print(repeated_strings_2) 不能在有默认参数后面跟随没有默认参数#f(a, b =2)合法#f(a = 2, b)非法关键字参数: 调用函数时，选择性的传入部分参数
def func(a, b = 4, c = 8): print('a is', a, 'and b is', b, 'and c is', c)func(13, 17)func(125, c = 24)func(c = 40, a = 80) VarArgs参数def print_paras(fpara, *nums, **words): print("fpara: " + str(fpara)) print("nums: " + str(nums)) print("words: " + str(words))print_paras("hello", 1, 3, 5, 7, word = "python", anohter_word = "java")