Removing an object from a vector by index - c++

Question

I have a for loop that looks like this:
for (int i = Particles.size() - 1; i >= 0; i--) {
if (Particles[i].Dead) {
Particles.erase(Particles.begin() + i);
}
}
When I compile, I get this error:
Error C2280 'Particle &Particle::operator =(const Particle &)': attempting to reference a deleted function
Gravity C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\include\xutility 2518
Anyone know what I'm doing wrong? Here's the particle code.
Header file
class Particle
{
public:
const float G = 6.674 * pow(10, -11);
float Mass, Radius;
Vector2 Position, Velocity, Force;
bool Dead = false;
void Gravity(Particle Particle2);
void Move();
void Draw(SDL_Surface *Surface, Uint32 Color);
Particle(float MassBounds[2], Vector2 PositionBounds[2], float Density);
Particle::Particle(float Mass, Vector2 Position, float Density, bool NonRandom);
Particle();
};
Source file
void Particle::Gravity(Particle Particle2)
{
float GravityMagnitude = (Particle::G*Mass*Particle2.Mass) / Vector2::DistanceSquared(Position, Particle2.Position);
Force += (Particle2.Position - Position).Normalised()*GravityMagnitude;
}
void Particle::Move()
{
Velocity += Force/Mass;
Position += Velocity;
}
void Particle::Draw(SDL_Surface *Surface, Uint32 Color)
{
if (int(Radius) > 0) { SDLDrawFilledCircle(Surface, int(Position.x), int(Position.y), Radius<1?1:int(Radius), Color); }
}
Particle::Particle(float MassBounds[2], Vector2 PositionBounds[2], float Density)
{
Mass = RandRange(MassBounds);
Position = Vector2(RandRange(PositionBounds[0].x, PositionBounds[1].x), RandRange(PositionBounds[0].y, PositionBounds[1].y));
Radius = pow((3.0 * Mass) / (4 * M_PI*Density), 1.0 / 3.0);
Velocity = Vector2();
Force = Vector2();
}
Particle::Particle(float Mass, Vector2 Position, float Density, bool NonRandom)
{
this->Mass = Mass;
this->Position = Position;
Radius = pow((3.0 * Mass) / (4 * M_PI*Density), 1.0 / 3.0);
Velocity = Vector2();
Force = Vector2();
}
Particle::Particle()
{
Mass = 1;
Position = Vector2();
Radius = 1;
Velocity = Vector2();
Force = Vector2();
}
inline bool operator==(const Particle& a, const Particle& b) { return a == b; }

Answer 1

You may have better luck using remove_if and erase:
#include <algorithm>
#include <iostream>
#include <vector>
using namespace std;
struct Vector {
int x;
int y;
};
bool is_negative (Vector a) {
return a.x < 0 && a.y < 0;
}
int main() {
vector<Vector> vectors;
vectors.push_back({-1, -2});
vectors.push_back({-1, 2});
vectors.push_back({1, 2});
vectors.push_back({-1, -2});
vectors.erase(
std::remove_if(vectors.begin(), vectors.end(), is_negative),
vectors.end());
for (auto v : vectors) {
cout << v.x << " " << v.y << endl;
}
}

Answer 2

I could not help notice this in your for loop:
Particles.erase(Particles.begin() + i-1)
More importantly
i - 1
You start with
i = Particles.size() - 1
and do not stop until
i < 0
This
Particles.begin()
gives you the head of the list.
When
i == 0
Particles.begin() + (i - 1)
will try to get invalid node.
Which translates to
Particles.begin() - 1
I do not know when your code breaks, I am going based on your loop
Here is link w/doc http://www.cplusplus.com/reference/vector/vector/erase/
Hope this helps