Three, python memory garbage collection and a collection of strings

Variable declaration:

name1 = "andy"

name2 = name1

 

This time I changed the value to name1 "tom", now ask what is the value name2? why?

A: andy, because you change the value of the equivalent of name1 name1 you will point to a new memory address called a tom, but still points to the old andy name2 memory address (string). Similarly java and c #

as follows

>>> name1 = "andy"

>>> name2 = name1

>>> id(name1)

47729824

>>> id(name2)

47729824

>>> name1 = "tom"

>>> id(name1)

47894176

>>> id(name2)

47729824

 

However, if the value is a collection of name1, then the situation is the opposite, that it is making changes in the original memory address if the value has changed name1, name2 values ​​will change along with

>>> name_list = ["rooney","linda","ramos"]

>>> id(name_list)

46820168

>>> name_list.append('pique')

>>> id(name_list)

46820168

 

to sum up:

Let me talk about strings: That you to change the string, not to say change your strings are specified in the original memory address, but opened a new string to store a memory address changes.

Such as: andy into tom, not a change in the memory address of the original andy points, but added a memory address is stored

Besides the collection: