CODEWITHSUNDEEP
c++list
Arthus V
Arthus V

Reputation: 29

Unable to delete a list element in C++

I am working on a small game and came across a big problem with lists.

Here's my code:

void cCollisionManager::checkCollision(cPlayer * pPlayer, std::list<cAsteroid*> *asteroidList, std::list<cShot*> *ShotList)
{       
    sf::FloatRect PlayerBox = pPlayer->getSprite()->getGlobalBounds();

    for (auto it : *asteroidList) {
        for (auto es : *ShotList) {
            sf::FloatRect asteroidboundingBox = it->getSprite()->getGlobalBounds();
            sf::FloatRect ShotBox = es->getSprite().getGlobalBounds();

            if (asteroidboundingBox.intersects(ShotBox)) {          

                it = asteroidList->erase(it);

                *pPlayer->pPunkte += 1;
                std::cout << *pPlayer->pPunkte << std::endl;
            }

            if (asteroidboundingBox.intersects(PlayerBox)) {
                if (*pPlayer->phealth >= 0.f)
                    *pPlayer->phealth -= 0.5f;
            }  
        }
    }
}

I used SFML and basically everything works. But if I want to delete the colliding asteroid and the shot, the programs exits with an error. In the if loop I tried to erase the object, but the compiler also gives an error saying that the argument type is not the same as the object type I am giving to it.

EDIT I had another look at the other question, you recommended to me, but still I haven't found out how to solve that problem. So if I changed my code to a while loop, the game couldn't handle it, because the Collision Manager is actually called in every single Call of the SFML main loop. So it would just get stuck in my collision loop. So I changed my code a bit, but still, things are not working.

Upvotes: 0

Views: 158

Answers (1)

Arthus V
Arthus V

Reputation: 29

Don't modify sequences that are being enumerated with range-for. Use iterators and the appropriate result of an erase. – WhozCraig

This is actually the answer to it. I did the mistake - using a for loop and not a while loop and so I had some big issues and bad construction ideas for my code - luckily everything now works! Here is my final code:

    auto it = asteroidList->begin();
auto es = ShotList->begin();

while (it != asteroidList->end()) {

    sf::FloatRect PlayerBox = pPlayer->getSprite()->getGlobalBounds();
    sf::FloatRect asteroidboundingBox = (*it)->getSprite()->getGlobalBounds();

    while (es != ShotList->end()) 
    {
        sf::FloatRect ShotBox = (*es)->getSprite().getGlobalBounds();

            if (asteroidboundingBox.intersects(ShotBox)) {
                it = asteroidList->erase(it);   
                es = ShotList->erase(es);   

                std::cout << "Asteroid destroyed" << std::endl;
                *pPlayer->pPunkte += 1;
                std::cout << *pPlayer->pPunkte << std::endl;
                }


        if (es != ShotList->end())
            es++;   

    }
        if (asteroidboundingBox.intersects(PlayerBox)) 
        {
            if (*pPlayer->phealth > 3.f) {
                *pPlayer->phealth -= 5.f;
                it = asteroidList->erase(it);   
            }   
            else
                *pPlayer->pBStateAlive = false;
        }


    if (it != asteroidList->end()) {
        it++;   
        es = ShotList->begin();     

    }


}

}

Upvotes: 1

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