Python 错误：赋值前引用了局部变量
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Python Error: local variable referenced before assignment
提问by hh54188
Here is my code:
这是我的代码：
import time
GLO = time.time()
def Test():
print GLO
temp = time.time();
print temp
GLO = temp
Test()
Traceback (most recent call last): File "test.py", line 11, in Test() File "test.py", line 6, in Test print GLO UnboundLocalError: local variable 'GLO' referenced before assignment
回溯（最近一次调用）：文件“test.py”，第 11 行，在 Test() 文件“test.py”，第 6 行，在测试中打印 GLO UnboundLocalError：赋值前引用的局部变量“GLO”
the error occurred when I add the GLO = temp, if I comment it, the function could be execute successfully, why?
添加时出现错误GLO = temp，如果我注释它，该函数可以成功执行，为什么？
How can I set GLO = temp?
我该如何设置GLO = temp？
回答by zhangyangyu
Python looks the whole function scope first. So your GLOrefers to the one below, not the global one. And refer the LEGB rule.
Python 首先查看整个函数作用域。所以你GLO指的是下面的那个，而不是全局的。并参考LEGB 规则。
GLO = time.time()
def Test(glo):
print glo
temp = time.time();
print temp
return temp
GLO = Test(GLO)
or
或者
GLO = time.time()
def Test():
global GLO
print GLO
temp = time.time();
print temp
GLO = temp
Test()
回答by Prahalad Deshpande
Within the Test method specify that you want to refer to the globally declared GLO variable as shown below
在 Test 方法中指定要引用全局声明的 GLO 变量，如下所示
def Test():
global GLO #tell python that you are refering to the global variable GLO declared earlier.
print GLO
temp = time.time();
print temp
GLO = temp
A similar question can be found here : Using a global variable within a method
可以在这里找到类似的问题： 在方法中使用全局变量
