Python Dictionary simple operation

1. Create

Two methods

The first type:

>>> a={}//DECLARE type First
>>> a[' a ']=1
>>> A

{' A ': 1}
The second type:

>>> b={' A ': 1, ' B ': 2}//create directly
>>> b
{' A ': 1, ' B ': 2}

2. Delete

Delete Develop Key-value

>>> del b[' B ']
>>> b
{' A ': 1}
Empty dictionary all Key-value

>>> b
{' A ': 1, ' C ': 4}

>>> B.clear ()
>>> b
{}
Completely delete dictionary this object!!!

>>> del b
>>> b
Traceback (most recent):
File "<stdin>", line 1, in <module>
Nameerror:name ' B ' is not defined

3. Adding elements to the dictionary

There are two different ways

>>> dict={}//After declaration or dict={' a ': 1}
>>> dict[' C ']=1
>>> Dict
{' C ': 1}
Another way to use SetDefault

>>> Dict.setdefault (' A ', ' QQQ ')
' QQQ '
>>> Dict
{' A ': ' QQQ ', ' C ': 1}

Not to be continued

Python Dictionary simple operation