CODEWITHSUNDEEP
c++vectoreraseprojectile
Adam Kenworthy
Adam Kenworthy

Reputation: 39

C++ vector erase crashes program

My program creates projectiles that move forward, if they go out of certain bounds, they are to be deleted from the vector that they are stored in. The vector stores xcord, ycord, zcord, and their respective directions.

int size = bullet.size();
        for(int i = 0; i < size; i+=6)
        {
                float xc = bullet[i];
                float yc = bullet[i+1];
                float zc = bullet[i+2];
                float xd = bullet[i+3];
                float yd = bullet[i+4];
                float zd = bullet[i+5];
                if(xc > 100 || yc > 10 || zc > 100 || xc < -100 || yc < -10 || zc < -100)
                {
                      bullet.erase(bullet.begin()+i, bullet.begin()+i+5);
                      size=size-6;
                      i = i-6;
                }
                else
                {
                     glEnable(GL_TEXTURE_2D);
                     glBindTexture ( GL_TEXTURE_2D, texture_id[3] );
                     glPushMatrix(); 
                     glTranslatef( xc+(xd/2), yc+(yd/2), zc+(zd/2));   //x y z coord of sphere
                     glRotatef( 0,0,1,0);
                     glRotatef( -80,1,0,0); 
                     glRotatef( 0,0,0,1); 
                     glScalef( 0.10f, 0.10f, 0.10f); 
                     gluQuadricTexture(quadric,1);
                     gluSphere(quadric,10.0,72,72); 
                     glPopMatrix();
                     glDisable(GL_TEXTURE_2D);
                     bullet[i] = xc+xd;
                     bullet[i+1] = yc+yd;
                     bullet[i+2] = zc+zd;
                }
        }

But when a "bullet" goes out of bounds my program seems to crash. Any ideas?

Well changing 

bullet.erase(bullet.begin()+i, bullet.begin()+i+5);

to

bullet.erase(bullet.begin()+i, bullet.begin()+i+6);

seems to have fixed it

For those interested

      bullet.push_back(xpos);
      bullet.push_back(0.0f);
      bullet.push_back(zpos);
      bullet.push_back(nxpos);
      bullet.push_back(nypos);
      bullet.push_back(nzpos);

happens whenever the mouse is clicked

Upvotes: 0

Views: 1888

Answers (2)

Tomer Arazy
Tomer Arazy

Reputation: 1823

http://www.cplusplus.com/reference/vector/vector/erase/

Iterators specifying a range within the vector] to be removed: [first,last). i.e., the range includes all the elements between first and last, including the element pointed by first but not the one pointed by last.

The problem is that you're deleting only 5 elements instead of 6.

Upvotes: 3

Luchian Grigore
Luchian Grigore

Reputation: 258618

You have

i < size

as your condition, and accessing elements

bullet[i] .... bullet[i+5]

See anything wrong there? What happens when i reaches size-1. You'll access bullet[size + 4], right?

Upvotes: 5

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