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Python中的字典与成员运算符初步探究

  • 时间:2022-08-10 04:10 编辑: 来源: 阅读:
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摘要:Python中的字典与成员运算符初步探究
[b]Python元字典[/b] 字典(dictionary)是除列表以外python之中最灵活的内置数据结构类型。列表是有序的对象结合,字典是无序的对象集合。 两者之间的区别在于:字典当中的元素是通过键来存取的,而不是通过偏移存取。 字典用"{ }"标识。字典由索引(key)和它对应的值value组成。
#!/usr/bin/python
# -*- coding: UTF-8 -*-

dict = {}
dict['one'] = "This is one"
dict[2] = "This is two"

tinydict = {'name': 'john','code':6734, 'dept': 'sales'}


print dict['one'] # 输出键为'one' 的值
print dict[2] # 输出键为 2 的值
print tinydict # 输出完整的字典
print tinydict.keys() # 输出所有键
print tinydict.values() # 输出所有值

输出结果为:
This is one This is two {'dept': 'sales', 'code': 6734, 'name': 'john'} ['dept', 'code', 'name'] ['sales', 6734, 'john']
[b]Python成员运算符[/b] 除了以上的一些运算符之外,Python还支持成员运算符,测试实例中包含了一系列的成员,包括字符串,列表或元组。 [img]http://files.jb51.net/file_images/article/201510/20151013145508304.jpg?2015913145549[/img] 以下实例演示了Python所有成员运算符的操作:
#!/usr/bin/python

a = 10
b = 20
list = [1, 2, 3, 4, 5 ];

if ( a in list ):
  print "Line 1 - a is available in the given list"
else:
  print "Line 1 - a is not available in the given list"

if ( b not in list ):
  print "Line 2 - b is not available in the given list"
else:
  print "Line 2 - b is available in the given list"

a = 2
if ( a in list ):
  print "Line 3 - a is available in the given list"
else:
  print "Line 3 - a is not available in the given list"

以上实例输出结果:
Line 1 - a is not available in the given list
Line 2 - b is not available in the given list
Line 3 - a is available in the given list
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