Python learning "5th article": Data types and Variables summary

strings, numbers, lists, tuples, dictionaries

Variable non-volatile

1. Variable: List

Such as:

>>> a = ["123", "xiaoxing"]

>>> ID (a)

4314085280

>>> a[0] = "Ceshi"

>>> ID (a)

4314085280

>>>

Here we first assign a value to the list A, get the ID (a), that is, the memory address is 4314085280

After we modify the value of the element in List A, the memory address of the re-acquisition of a is still unchanged, but the internal value has been modified, so the list is mutable.

2. Immutable: string, number, tuple

The string immutable example is as follows:

>>> name = "Xiao"

>>> ID (name)

4314237280

>>> name = "Xing"

>>> ID (name)

4314237424

>>>

Here we assign a value to the variable first Xiao, get the memory address is 4314237280, when we assign the variable again worth time, again get memory address discovery has changed, equivalent to the original created variable memory address is immutable

and cannot be modified, so the re-assignment requires a re-opening of the memory address, so it is immutable

Access Order:

1. Sequential access: strings, lists, tuples

2. Mapping: Dictionaries

Number of elements to store:

Container type: list, tuple, dictionary (represents can hold multiple values)

Atomic type: Number, string (represents can hold a value)

Python learning "5th article": Data types and Variables summary