为什么允许擦除 vector.end()? [英] Why erasing vector.end() is allowed?

问题描述

今天我正在做一些代码，看起来像这样:

Today I was doing a bit of code, which looked something like this:

vec.erase(std::remove_if(vec.begin(), vec.end(), <lambda here>));

当上面的代码不应该擦除任何东西时，这意味着 std::remove_if 应该返回 vec.end()，当我收到大小减一的向量时，我感到非常惊讶:最后一个元素被擦除了.问题已通过将以上更改为:

When above code was not supposed to erase anything, meaning that std::remove_if should return vec.end(), I was very surprised when i received my vector with size decreased by one: last element was erased. Problem was fixed by changing above to:

vec.erase(std::remove_if(vec.begin(), vec.end(), <lambda here>), vec.end());

但问题仍然存在:怎么做

But still question remains: how can

vec.erase(vec.end());

有工作吗?不应该是未定义的行为吗?

do any work? Shouldn't it be undefined behaviour?

显然，我对未定义行为的理解从一开始就是错误的，我一直观察到的是 UB.谢谢大家回答我的问题.

Apparently my understanding of underfined behaviour was wrong from the beginning and what i observed was UB all along. Thank you everyone for answering my question.

推荐答案

它是未定义的行为.特别是，这意味着您可能会看到大小减少了一个

It is undefined behaviour. In particular, it means that you may see size decreased by one

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