print(f"通过关键字参数创建的字典: { <!-- -->person_details}") # 输出: 通过关键字参数创建的字典: {'name': '李四', 'age': 25, 'city': '上海'} # 如果键不是有效的标识符,例如包含空格或以数字开头,这种方式会报错 # dict(first name="王五") # 这会引发 SyntaxErro
使用item()就有点类似于php里的foreach类似。都能把键=>值的方式遍历出来,如果纯使用for..in则只能取得每一对元素的key值 代码如下: person={'name':'lizhong','age':'26','city':'BeiJing','blog':'www.jb51.net'} for x in person: print x 执行结果:...
For example, to copy an existing dictionary and append a new item, see the following code: my_dictionary = { "one": 1, "two": 2 } new_dictionary = {**my_dictionary, **{"three":3}} print(new_dictionary)Copy The new dictionary contains the added item while preserving the old dictio...
popitem()methodofbuiltins.dictinstanceRemoveandreturna(key,value)pairasa2-tuple.PairsarereturnedinLIFO(last-in,first-out)order.RaisesKeyErrorifthedictisempty. LIFO ,即“Last in, First out”,译为“后进先出”,这是计算机科学中插入、删除数据一种原则,例如,一种名为栈( Stack )的数据结构,只能在栈...
scores={"Alice":85,"Bob":92,"Charlie":78,"David":90}first_data=[itemforiteminscores.items()][0]student_name,score=first_dataprint("学生姓名:",student_name)print("成绩:",score) 1. 2. 3. 4. 5. 6. 7. 8. 代码执行的结果如下所示: ...
('goose', 3), ('duck', 4)] #输出都一样 >>> print(d1,d2,d3,sep='\n') {'cat': 0, 'dog': 1, 'bird': 2, 'goose': 3, 'duck': 4} {'cat': 0, 'dog': 1, 'bird': 2, 'goose': 3, 'duck': 4} {'cat': 0, 'dog': 1, 'bird': 2, 'goose': 3, 'duck'...
dict= {'Name':'Zara','Age': 7,'Class':'First'};print"dict['Alice']:", dict['Alice']; 以上实例输出结果: #KeyError: 'Alice'[/code] 三、修改字典 向字典添加新内容的方法是增加新的键/值对,修改或删除已有键/值对如下实例: dict= {'Name':'Zara','Age': 7,'Class':'First'}; ...
In[95]:foriincity2.keys(): ...print(i) ... first second forth fifth 5.删除方法——pop() & popitem() pop()——删除该键值对,并返回值。如果没有该键,可以返回信息或报错。 In[96]: city Out[95]: {'first':'beijing','second':'shanghai'} ...
print( "黑马程序员" ) >>666 >>13.14 >>"黑马程序员" (二) 注释 1. 单行注释 # 我是单行注释 print( "黑马程序员" ) !规范:#号和注释内容一般建议以一个空格隔开 2. 多行注释 """ 我是多行注释 666 13.14 "黑马程序员" """ print( 666 ) ...
When the resultant getter receives the tuple, it returns the first item in the tuple—the value at index 0. If you call itemgetter() with an argument of 1, then it gets the value at index position 1.You can use this itemgetter as a key for the sorted() function:...