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Python全局变量操作详解

Jun 10, 2016 pm 03:15 PM
python

接触Python时间不长,对有些知识点,掌握的不是很扎实,我个人比较崇尚不管学习什么东西,首先一定回去把基础打的非常扎实了,再往高处走。今天遇到了Python中的全局变量的相关操作,遇到了问题,所以,在这里将自己遇到的问题,做个记录,以长记心!!!

在Python中使用全局变量,其实,个人认为并不是很明智的选择;但是自己还是坚信,存在便合理,在于你怎么使用;全局变量降低了模块和函数之间的通用性;所以,在以后的编程过程中,应尽量避免使用全局变量。

全局变量的使用:

方法一:

为了便于代码管理,将全局变量统一放到一个模块中,然后在使用全局变量的时候,导入全局变量模块,通过这种方法来进行使用全局变量;
在一个模块中定义全局变量:

复制代码 代码如下:

#global.py 
GLOBAL_1 = 1 
GLOBAL_2 = 2 
GLOBAL_3 = 'Hello World' 

然后在一个模块中导入全局变量定义模块,在新模块中使用全局变量:
复制代码 代码如下:

import globalValues 
 
def printGlobal(): 
    print(globalValues.GLOBAL_1) 
    print(globalValues.GLOBAL_3) 
    globalValues.GLOBAL_2 += 1 # modify values 
 
if __name__ == '__main__': 
    printGlobal() 
    print(globalValues.GLOBAL_2) 

方法二:

直接在模块中定义全局变量,然后在函数中直接使用就ok了。但是在使用全局变量的时候,必须在函数中使用global关键字进行标识:

复制代码 代码如下:

CONSTANT = 0 
 
def modifyGlobal(): 
    global CONSTANT 
    print(CONSTANT) 
    CONSTANT += 1 
 
if __name__ == '__main__': 
    modifyGlobal() 
    print(CONSTANT) 

讲解完毕!!!

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