python学习指南之字典

字典的value可以是任何python对象。操作非常灵活。
字典数据结构中存在的基本操作 ：

• 访问字典
• 添加key-value对
• 修改字典value
• 删除key-value
• 遍历字典

删除key-value

dict = {"one":3, "two":"hello,world", "three":23.8, "four":True};
print "原来的字典序列:",dict;

del dict["one"];
print "删除后的字典序列:", dict;

输出的结果是：

原来的字典序列: {'four': True, 'three': 23.8, 'two': 'hello,world', 'one': 3}
删除后的字典序列: {'four': True, 'three': 23.8, 'two': 'hello,world'}

遍历字典

遍历key-value对

dict = {"one":3, "two":"hello,world", "three":23.8, "four":True};
for key,value in dict.items():
    print "key=",key,
    print "value=", value;

输出的结果是：

key= four value= True
key= three value= 23.8
key= two value= hello,world
key= one value= 3

遍历key

dict = {"one":3, "two":"hello,world", "three":23.8, "four":True};
for key in dict.keys():
    print "key=",key;

输出的结果是：

key= four
key= three
key= two
key= one

遍历value

dict = {"one":3, "two":"hello,world", "three":23.8, "four":True};
for value in dict.values():
    print "value=",value;

输出的结果是：

value= True
value= 23.8
value= hello,world
value= 3