从向量中删除元素 [英] Deleting elements from a vector
本文介绍了从向量中删除元素的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
下面的C ++代码用一些对象填充一个向量,然后删除一些对象,但它看起来像删除了错误的对象:
The following C++ code fills a vector with a number of objects and then removes some of these objects, but it looks like it deletes the wrong ones:
vector<Photon> photons;
photons = source->emitPhotons(); // fills vector with 300 Photon objects
for (int i=0; i<photons.size(); i++) {
bool useless = false;
// process photon, set useless to true for some
// remove useless photons
if (useless) {
photons.erase(photons.begin()+i);
}
}
我这样做是否正确?我认为 photons.erase(photons.begin()+ i);
可能是问题?
Am I doing this correctly? I'm thinking the line photons.erase(photons.begin()+i);
might be the problem?
推荐答案
这是错误的做法,你从来不调整 i
下来,因为你删除..
Definietly the wrong way of doing it, you never adjust i
down as you delete..
使用迭代器,这个问题消失了!
Work with iterators, and this problem goes away!
例如
for(auto it = photons.begin(); it != photons.end();)
{
if (useless)
it = photons.erase(it);
else
++it;
}
还有其他方法使用算法(如 remove_if
和 erase
等),但上面是最清晰的...
There are other ways using algorithms (such as remove_if
and erase
etc.), but above is clearest...
这篇关于从向量中删除元素的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!
查看全文