如何从它的 try catch 块内部中断 for 循环？

Question

如果 try except 块内的代码块（在 for 循环内）成功执行，而不是调用异常，我正在尝试找到一种方法来摆脱这个 for 循环。

这是对我不起作用的代码：

attempts = ['I15', 'J15']
for attempt in attempts:
    try:
        avar = afunc(attempt)
        break
    except KeyError:
        pass
        if attempt == attempts[-1]:
            raise KeyError

因为在I15成功执行后，它仍然在调用尝试列表中的J15项

这里的代码：

    except KeyError:
        pass
        if attempt == attempts[-1]:
            raise KeyError

用于抛出实际的异常，如果代码已经尝试了整个attempt的attempts

Answer 1

你需要for … else概念： https : //docs.python.org/3/tutorial/controlflow.html#break-and-continue-statements-and-else-clauses-on-loops

attempts = ['I15', 'J15']
for attempt in attempts:
    try:
        avar = afunc(attempt)
    except KeyError:
        # error, let's try another item from attempts
        continue
    else:
        # success, let's get out of the loop
        break
else:
    # this happens at the end of the loop if there is no break
    raise KeyError

Answer 2

我相信最干净的方法是在except块内continue ，并在它之后break ing。 在这种情况下，您甚至不必使用avar （除非我误解了这个问题）。

attempts = ['I15', 'J15']
for attempt in attempts:
    try:
        afunc(attempt)
    except KeyError:
        continue
    break

如果您确实需要avar以供以后使用：

attempts = ['I15', 'J15']
for attempt in attempts:
    try:
        avar = afunc(attempt)
    except KeyError:
        continue
    break
print(avar) # avar is a available here, as long as at least one attempt was successful