Python的基础语法（二）

Python的基础语法（二）

Tuple数据类型：

mixed_tuple = (1 , 2, ['a','b'])print("mixed_tuple:" + str(mixed_tuple))mixed_tuple[2][0]='c'mixed_tuple[2][1]='d'print("mixed_tuple after:" + str(mixed_tuple))

字典的应用：

# coding: utf-8# 创建一个词典phone_book= {'Tom':123,'sunliyuan':456,'shi':789}mixed_dict={"Tom":'boy',11:23.5}# 字典的调用print ("sunliyuan has phone numbr:"+ str(phone_book["sunliyuan"]))# 修改字典的值phone_book['sunliyuan']=521print ("sunliyuan has phone numbr:"+ str(phone_book["sunliyuan"]))# 添加一个值phone_book['sunli']=888print ("sunliyuan has phone numbr:"+ str(phone_book))# 删除字典中的元素和本身del phone_book['sunli']print ("sunli after del is:"+ str(phone_book))# 清空字典的值phone_book.clear()print ("sunli after del is:"+ str(phone_book))# 清空字典本身del phone_bookprint ("sunli after del is:"+ str(phone_book))

运行的效果图：

# 特性# 不允许同一个键出现两次rep_test={'Name':'aa','age':5,'Name':'sun'}print("rep_test:"+str(rep_test))# 键必须不可变 用数字和字符串充当键 不能用list充当# list_dict={['Name']:'sun','Age':13}#Tuple是可以的 （可变的）list_dict={('Nam'):'sun','Age':13}

函数：

# coding: utf-8# 没有参数和返回的函数def say_hi(): print ("sunliyuan") say_hi() say_hi()# 有参数 无返回值 def print_sum(a,b): c=a+b print (c) print_sum(1,2) def hellow(str): print("hellow" + str + "!")# 有参数有返回值的def repatstr(str,times): repeated_strs=str*times return repeated_strs repatstr_string=repatstr("sunliyuan",4) print(repatstr_string)# 全局变量和局部变量x = 60def 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")

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