我如何在Python函数中使用全局变量? [英] How do I use global variables in python functions?
问题描述
如何在python函数中设置一个全局变量?
global
函数内的变量,您需要在函数内部执行 global< varName>
,就像这样。 testVar = 0
def testFunc():
全局testVar
testVar + = 1
print testVar
testFunc()
print testVar
给出输出
>>>
0
1
请记住,您只需要声明它们全局
在函数内部,如果你想做赋值/改变它们。 全球
不需要打印和存取。
您可以这样做,
def testFunc2():
print testVar
没有像第一个函数那样声明它<
以列表
为例,您不能指定 list
没有声明它全局
,但你可以调用它的方法并改变列表。如下。
testVar = []
def testFunc1():
testVar = [2]#将创建一个本地testVar并将其分配[2],但不会更改全局变量。
def testFunc2():
全局testVar
testVar = [2]#将改变全局变量。
def testFunc3():
testVar.append(2)#将改变全局变量。
How do I set a global variable inside of a python function?
To use global
variables inside a function, you need to do global <varName>
inside the function, like so.
testVar = 0
def testFunc():
global testVar
testVar += 1
print testVar
testFunc()
print testVar
gives the output
>>>
0
1
Keep in mind, that you only need to declare them global
inside the function if you want to do assignments / change them. global
is not needed for printing and accessing.
You can do,
def testFunc2():
print testVar
without declaring it global
as we did in the first function and it'll still give the value all right.
Using a list
as an example, you cannot assign a list
without declaring it global
but you can call it's methods and change the list. Like follows.
testVar = []
def testFunc1():
testVar = [2] # Will create a local testVar and assign it [2], but will not change the global variable.
def testFunc2():
global testVar
testVar = [2] # Will change the global variable.
def testFunc3():
testVar.append(2) # Will change the global variable.
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