如何從它的 try catch 塊內部中斷 for 循環？

Question

如果 try except 塊內的代碼塊（在 for 循環內）成功執行，而不是調用異常，我正在嘗試找到一種方法來擺脫這個 for 循環。

這是對我不起作用的代碼：

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

因為在I15成功執行后，它仍然在調用嘗試列表中的J15項

這里的代碼：

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

用於拋出實際的異常，如果代碼已經嘗試了整個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

我相信最干凈的方法是在except塊內continue ，並在它之后break ing。 在這種情況下，您甚至不必使用avar （除非我誤解了這個問題）。

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

如果您確實需要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