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