Python 范围:“UnboundLocalError:在赋值之前引用了局部变量‘c’"； [英] Python scope: "UnboundLocalError: local variable 'c' referenced before assignment"

问题描述

我正在尝试解决这个问题:

I am trying to figure out this:

c = 1
def f(n):
    print c + n 
def g(n):
    c = c + n

f(1) # => 2
g(1) # => UnboundLocalError: local variable 'c' referenced before assignment

谢谢！

推荐答案

在函数内，默认情况下，分配给的变量被视为局部变量.要分配给全局变量，请使用 global 声明:

Within a function, variables that are assigned to are treated as local variables by default. To assign to global variables, use the global statement:

def g(n):
    global c
    c = c + n

这是 Python 的古怪领域之一，我从来没有真正适应过.

This is one of the quirky areas of Python that has never really sat well with me.

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