python--about connectors +

Connector +

Connector + actually creates a new object and consumes new memory (DICT, set cannot be used)

String

Because Python must allocate new memory for each string that uses the connector +, and produce a new string. The following two ways are more effective

① using the format operator (%)

>>> '%s%s '% (' hello ', ' world ')

' Hello World '
>>>

　　　② the string into the list, using the join connection

>>> ' _ '. Join ([' Hello ', ' world ')

' Hello_world '
>>>

List

Ibid., two lists using + Connect is the generation of a new list. can be list.extend () instead of +

>>> p = [+ +]

　　　　>>> pp = [4,5,6]
>>> p.extend (PP)
>>> P
[1, 2, 3, 4, 5, 6]
>>>

python--about connectors +