从向量中擦除向量::end
当我使用时它是否正常工作(什么都不做)
Does it works correct(does nothing) when I use
vector<T> v;
v.erase(v.end());
我想使用类似的东西
v.erase(std::find(...));
我应该 if 是 v.end() 还是不是?
C++.com 和 CPPreference
Should I if is it v.end() or not?
There is no info about it on C++.com and CPPreference
推荐答案
标准并没有完全说明，但是 v.erase(q) 是定义的，擦除指向的元素通过 [sequence.reqmts] 中的 q".这意味着 q 必须实际指向一个元素，而结束迭代器没有.传入 end 迭代器是未定义的行为.
The standard doesn't quite spell it out, but v.erase(q) is defined, "Erases the element pointed to by q" in [sequence.reqmts]. This means that q must actually point to an element, which the end iterator doesn't. Passing in the end iterator is undefined behavior.
不幸的是，你需要写:
auto it = std::find(...);
if (it != <the part of ... that specifies the end of the range searched>) {
v.erase(it);
}
当然，你可以定义:
template typename<Sequence, Iterator>
Iterator my_erase(Sequence &s, Iterator it) {
if (it == s.end()) return it;
return s.erase(it);
}
my_erase(v, std::find(v.begin(), v.end(), whatever));
关联容器上的
c.erase() 返回 void，因此要将这个模板推广到所有容器，您需要一些 ->decltype 动作.
c.erase() on an associative container returns void, so to generalize this template to all containers you need some -> decltype action.
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