如何理解 Python 中的全局和局部作用域？
How to understand global and local scopes in Python?
我是Python的新手，想知道下面的情况
x = 1
def func():
print(x)
x = 2
return x
所以我得到了 UnboundLocalError: local variable 'x' referenced before assignment。
但是，如果我理解正确的话——Python 逐行读取和执行代码。
因此，在函数“print(x)”内的第一个语句中，它必须只传递全局变量 x which eq。 1，但我得到了错误。
请解释一下，我觉得很简单。
我认为 python docs
的常见问题解答中也解释了您的问题
This is because when you make an assignment to a variable in a scope,
that variable becomes local to that scope and shadows any similarly
named variable in the outer scope. Since the last statement in foo
assigns a new value to x, the compiler recognizes it as a local
variable. Consequently when the earlier print(x) attempts to print the
uninitialized local variable and an error results.
我是Python的新手，想知道下面的情况
x = 1
def func():
print(x)
x = 2
return x
所以我得到了 UnboundLocalError: local variable 'x' referenced before assignment。 但是，如果我理解正确的话——Python 逐行读取和执行代码。 因此，在函数“print(x)”内的第一个语句中，它必须只传递全局变量 x which eq。 1，但我得到了错误。 请解释一下，我觉得很简单。
我认为 python docs
的常见问题解答中也解释了您的问题This is because when you make an assignment to a variable in a scope, that variable becomes local to that scope and shadows any similarly named variable in the outer scope. Since the last statement in foo assigns a new value to x, the compiler recognizes it as a local variable. Consequently when the earlier print(x) attempts to print the uninitialized local variable and an error results.