Python中的字典与成员运算符初步探究

Python元字典
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\']

Python成员运算符
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。

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