“ this”指针有什么问题？

Question

So, i decided to create a collision detection function in my game and i put it into the class of enemies. Then i put it to "enemy.cpp" and i used "this" pointer. The code:

if(((this->sprite.getPosition().y + this->sprite.getTextureRect().height) >= blocklist[i].sprite.getPosition().y) &&
(this->sprite.getPosition().y  <= blocklist[i].sprite.getPosition().y))

This gives me SIGSEGV segmentation error. I can't find what could be the problem in this line, here is the enemyclass for reference.

class enemyclass
{
public:
    sf::Sprite sprite;
    sf::Sprite bubble;
    //PROPERTIES
    float xspeed, yspeed;
    int x, y;
    float health;
    bool colR, colL, colU, colD;
    int skin;
    void detectCollisions(int blocksize);
};

and the blockclass that i made a vector of to use as a list of enemies:

class blockclass
{
public:
    sf::Sprite sprite;
    int x, y;
};

I would be very thankfull for an answer since i can't find out what's wrong.

Answer 1

As others have said, if some complicated instruction causes an error, split it into smaller parts and see, in which part the error arises:

if( this->x == 0) // changes nothing
    x = 0;        // but validates 'this'
int thisy = sprite.getPosition().y;
int thish = sprite.getTextureRect().height;
sf::Sprite &that = blocklist[i].sprite;
if( that.x == 0) // validate 'that'
    that.x = 0;
int thaty = that.getPosition().y;
if(thisy + thish >= thaty && thisy <= thaty) {
    // ......
}