Python learning path: day3; python path: day3

Python learning path: day3; python path: day3

 

When assigning values, copying values, and copying values to dictionaries, parent databases, and lists, the memory address varies. For convenience, I copied the instructor's

 

1. Assignment

 

Assignment, Just create a variable that points to the original memory address, such:

 

123	n1 = {"k1": "wu", "k2": 123, "k3": ["alex", 456]}  n2 = n1

 

　　

 

2. Shallow copy

 

Shortest copyOnly the first layer of data is created in the memory.

 

12345

import copy  n1 = {"k1": "wu", "k2": 123, "k3": ["alex", 456]}  n3 = copy.copy(n1)

 

 

3. Deep copy

 

Deep copy, Re-create a copy of all data in the memory (excluding the last layer, namely, optimizing strings and numbers in python)

 

12345

import copy  n1 = {"k1": "wu", "k2": 123, "k3": ["alex", 456]}  n4 = copy.deepcopy(n1)

 

 

 

 

Function

Functions are divided into user-defined functions and python built-in functions.

Definition:

A function encapsulates a set of statements by a name (function name). to execute this function, you only need to call its function name.

Syntax definition:

Def hello (): # hello is the function name, And the def keyword is used to create the function print ("hello world...") hello () # Call the Function

 

Function execution process:

1. def Keyword: Create a function

2. Function Name

3 ,()

4. Function body (the function body is not executed by default and executed when I call it)

5. return values

Function features:

1. reduce repeated code

2. It is a scalable program.

3. The program has become maintained.