python 函数的基础知识

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）

用关键字 ‘def' 来定义，identifier(参数),参数为list

#-*- 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))

def repeat_str(s, times = 1):
    repeated_strs = s * times
    return repeated_strs

repeated_strings = repeat_str("Happy Birthday!")
print(repeated_strings)

repeated_strings_2 = repeat_str("Happy Birthday!" , 4)
print(repeated_strings_2)

#f(a, b =2)合法
#f(a = 2, b)非法

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)

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")