std :: remove_if无法正常工作 [英] std::remove_if not working properly

问题描述

这是我的代码.我想从向量中删除所有成功调用方法'release'的元素.

Here my code. I want remove from vector all elements with successfully called method 'release'.

bool foo::release()
{
    return true;
}

// ...
vector<foo> vec;
// ...
remove_if(vec.begin(), vec.end(), [](foo & f) { return f.release() == true; });
// ...

但是remove_if不会删除vector vec中的所有元素. remove_if如何工作?

But remove_if not deleting all elements from vector vec. How remove_if works?

推荐答案

std::remove_if 重新排列矢量的元素，使要保留的元素在[vec.begin(), return_iterator)范围内(请注意部分打开的范围).因此，您需要调用std::vector::erase以确保向量仅包含所需的元素.这称为 擦除-删除惯用语 :

std::remove_if re-arranges the elements of the vector such that the elements you want to keep are in the range [vec.begin(), return_iterator) (note the partially open range). So you need to call std::vector::erase to make sure the vector contains only the desired elements. This is called the erase-remove idiom:

auto it = remove_if(vec.begin(),
                    vec.end(),
                    [](foo & f) { return f.release() == true; });

vec.erase(it, vec.end());

在这里，为了清楚起见，我将其分为两行，但通常将其视为一线.

Here, I have split it into two lines for clarity, but it is often seen as a one-liner.

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