Definition and usage analysis of local and global variables in python (example)

In this article, let’s take a look at the variables in the python programming language, that is, is python global variables and local variables, and the variables in python are divided into global variables Variables and local variables, two types of variables. In fact, we can easily understand the difference between global variables and local variables through the difference between these two names. Okay, without further ado, let’s start understanding these two variables.

First we need to knowVariable scope:Not all variables of a program can be accessed from all locations. Access permissions depend on where the variable is assigned.

The scope of a variable determines which part of the program you can access which specific variable name. The two most basic variable scopes are as follows:

Global variables

Local variables

Global variables and Local variables: Variables defined inside a function have a local scope, and variables defined outside the function have a global scope.

Local variables can only be accessed within the function in which they are declared, while global variables can be accessed throughout the entire program. When a function is called, all variable names declared within the function will be added to the scope. The following example:

#!/usr/bin/python
# -*- coding: UTF-8 -*-
 
total = 0; # 这是一个全局变量
# 可写函数说明
def sum( arg1, arg2 ):
   #返回2个参数的和."
   total = arg1 + arg2; # total在这里是局部变量.
   print "函数内是局部变量 : ", total
   return total;
 
#调用sum函数
sum( 10, 20 );
print "函数外是全局变量 : ", total

The output value of the above example is as follows:

函数内是局部变量 :  30
函数外是全局变量 :  0

The above is what I want to explain today, the respective definitions and functions of global variables and local variables, just The explanations and examples I gave are just words on paper. Hands-on practice is the best way to verify what you have learned. Finally, I hope this article can bring some help to you who are learning python.

For more related knowledge, please visit the Python tutorial column on the php Chinese website.

The above is the detailed content of Definition and usage analysis of local and global variables in python (example). For more information, please follow other related articles on the PHP Chinese website!