Python alter external variable from function

在Python中，可以通过函数来修改外部变量。Python中的变量作用域分为全局作用域和局部作用域。全局作用域中定义的变量可以在整个程序中访问，而局部作用域中定义的变量只能在函数内部访问。

要在函数中修改外部变量，可以使用global关键字将变量声明为全局变量。这样，在函数内部对该变量的修改将影响到外部的变量。

下面是一个示例：

x = 10

def modify_variable():
    global x
    x = 20

print("Before modification:", x)
modify_variable()
print("After modification:", x)

输出结果为：

Before modification: 10
After modification: 20

在上面的示例中，通过在函数内部使用global关键字声明变量x为全局变量，然后在函数内部将其修改为20。最后打印变量x的值，可以看到外部的变量也被成功修改了。

需要注意的是，在函数内部使用global关键字声明变量为全局变量后，对该变量的任何修改都会影响到全局作用域中的变量。因此，在使用global关键字时要谨慎，确保修改的变量是我们想要修改的。

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Python alter external variable from function

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