Python 3 Grammar Note (5): Dictionary

As you can see from the previous sections, Python is the most basic type of programming language.

• List
• Tuple
• Set
• Dict

It can be seen that the granularity of segmentation in data structure is to satisfy the need of more domain programming.

1 Creating a dictionary

Other methods, such as list and tuple, can also be created, see the manual. The keys of a dictionary are non-repeatable and are somewhat similar in nature to the set of set,dict that can be understood as carrying values. Of course Dict does not have a set operation method (intersection, set, difference set, etc.).

2 Reading and writing dictionaries

a_dict[' database ' = ' blog '            #database键如不存在表示增加, exists is to change the value

Reading a nonexistent key throws a Keyerror exception.

3 except for strings, read-only types can be used as keys to dictionaries

suffixes = {: [' KB ', ' MB ', ' GB ', ' TB ', ' PB ', ' EB ', ' ZB ', ' YB '],            1024x768: [' KiB ', ' MiB ', ' GiB ', ' TiB ', ' PiB ', ' EiB ', ' ZiB ', ' Yib ']}

4 Boolean Test

{} indicates false, non {} indicates true

5 None

Like other languages, NULL, which belongs to the Nonetype type, has only one value.

At the Boolean test plane none is False,not none is true.

Python 3 Grammar Note (5): Dictionary