Why is my ball using acceleration as velocity? - c++

Question

I got an object of type ball which is a subclass of the class Particle. This class has three members position, velocity and acceleration of type Vector.
On each frame, when myball.update is called, its velocity is summed to the position and the acceleration is summed to the velocity. Then the ball is drawn on the screen. Anyway for some unclear motive whatever value I give as a velocity the ball doesn't move, but it moves in non - accelerated uniform movement if I give a value as the acceleration.
Here are my classes Vector:
class Vector {
private:
void updateC() {
x = cos(a) * l;
y = sin(a) * l;
}
void updateT() {
a = atan2(y, x);
l = sqrt(x * x + y * y);
}
public:
float x = 0, y = 0;
float a = 0, l = 0;
Vector() {
}
Vector(float nx, float ny): x(nx), y(ny) {
updateT();
}
void X(float nx) {
x = nx;
updateT();
}
void Y(float ny) {
y = ny;
updateT();
}
void A(float na) {
a = na;
updateC();
}
void L(float nl) {
l = nl;
updateC();
}
Vector operator +(Vector other) {
return Vector(x + other.x, y + other.y);
}
Vector operator -(Vector other) {
return Vector(x - other.x, y - other.y);
}
Vector operator *(float m) {
Vector result(x, y);
result.L(l * m);
return result;
}
void operator +=(Vector other) {
x += other.x;
y += other.y;
updateT();
}
void operator -=(Vector other) {
x -= other.x;
y -= other.y;
updateT();
}
void operator *=(float m) {
l *= m;
updateC();
}
};
Particle:
class Particle {
public:
Vector position;
Vector velocity;
Vector gravity;
Particle() {}
Particle(Vector np, Vector nv = Vector(0, 0), Vector na = Vector(0, 0)): position(np), velocity(na), gravity(na) {}
void accelerate(Vector a) {
velocity += a;
}
void update() {
position += velocity;
velocity += gravity;
}
};
And ball:
class ball: public Particle {
public:
ball(Vector p, Vector v, Vector a): Particle(p, v, a) {}
void update() {
Particle::update();
graphics.circle("fill", position.x, position.y, 10);
}
};
So, as I said before, if I initialize myball with a velocity different than 0, the ball still won't move, but it will move if I inititialize it with an acceleration different than 0 using acceleration as velocity.
What did I do wrong?

Answer 1

You have a typo in the Particle constructor:
Particle(Vector np, Vector nv = Vector(0, 0), Vector na = Vector(0, 0)): position(np), velocity(na), gravity(na) {}
It must be:
Particle(Vector np, Vector nv = Vector(0, 0), Vector na = Vector(0, 0)): position(np), velocity(nv), gravity(na) {}