C++ 向量迭代器不是增量的

Question

I've been having a headache with this problem. I've challenged myself to make a CLI space shooter, where you have you spaceship, lasers and meteors to shoot. The problem is this: whenever a laser or a meteor reaches the boundaries of our arena, I want to erase from the vector so that it wouldn't cluster it up. Here's how my working code looks now:

        std::vector<Meteoras>::iterator itMet = meteorai.begin();
        std::vector<Lazeris>::iterator itLaz = lazeriai.begin();
        while (itMet != meteorai.end() || itLaz != lazeriai.end())
        {
            if (itLaz != lazeriai.end())
            {
                if (itLaz->getCoord()->x == j && itLaz->getCoord()->y == i)
                {
                    itLaz->move(); 
                    ++j; 
                    if (itLaz->getCoord()->x >= ILGIS - 1) continue;
                    else std::cout << itLaz->getIcon();
                }
                ++itLaz;
            }
            if (itMet != meteorai.end())
            {
                if (itMet->getCoord()->x - 1 == j && itMet->getCoord()->y == i)
                {
                    itMet->move();
                    ++j;
                    if (itMet->getCoord()->x <= 0) continue;
                    else std::cout << itMet->getIcon();
                }
                ++itMet;
            }
        }

So there are two "continues" in there. Instead of them I tried placing iterator removals (as in itLaz = lazeriai.erase(itLaz) but that the program seemed to crash during runtime giving the error that I stated before. I tried doing other logical checks but that didn't seem to work either. I would appreciate if someone could explain a proper way of removing a useless object (in this case a meteor/laser) from a vector.

Answer 1

The comment about erase() invalidating an iterator is true. The part about needing to restart at the beginning is wrong. (You could do, but you certainly don't need to.)

erase() returns a still-valid iterator which points to the element after the erased item.

if( test for erasing )
{
    itLaz = lazeriai.erase(itLaz);
}
else
{
   ++itlaz;
}

You might be able to refactor your code to use std::remove_if() instead.