How to break out of multiple loops in Python?

Given the following code (that doesn't work):

while True:
    #snip: print out current state
    while True:
        ok = get_input("Is this ok? (y/n)")
        if ok == "y" or ok == "Y": break 2 #this doesn't work :(
        if ok == "n" or ok == "N": break
    #do more processing with menus and stuff

Is there a way to make this work? Or do I have do one check to break out of the input loop, then another, more limited, check in the outside loop to break out all together if the user is satisfied?

Edit-FYI: get_input is a short function I wrote that supports showing a prompt and default values and all that fanciness and returns stdin.readline().strip()

---

我的第一本能是将嵌套循环重构成一个函数，并使用return来分解。

---

PEP 3136 proposes labeled break/continue. Guido rejected it because "code so complicated to require this feature is very rare". The PEP does mention some workarounds, though (such as the exception technique), while Guido feels refactoring to use return will be simpler in most cases.

---

Here's another approach that is short. The disadvantage is that you can only break the outer loop, but sometimes it's exactly what you want.

for a in xrange(10):
    for b in xrange(20):
        if something(a, b):
            # Break the inner loop...
            break
    else:
        # Continue if the inner loop wasn't broken.
        continue
    # Inner loop was broken, break the outer.
    break

---

(Bystander-EDIT here, because we haven't seen @yak in a looong time.)

Key insight: It only seems as if the outer loop always breaks. But if the inner loop doesn't break, the outer loop won't either.

The continue statement is the magic here. It's in the for-else clause. By definition that happens if there's no inner break. In that situation continue neatly circumvents the outer break.

链接地址: http://www.djcxy.com/p/36320.html

上一篇: 如何摆脱每个循环的jQuery

下一篇: 如何摆脱Python中的多个循环？