Thread: A vector of structs problem

Hello all,

Trying to work on some code - a struct with spring variables is loaded into a vector in an insert function, but the vector is empty in later functions. I suspect it has something to do with scopes or something, but am relatively new to std::vectors.

I think it is a relatively simple problem, so will just post the bits of code related to the vector (rather than a runnable program). Apologies for any confusion, but there is also another 'Vector' class used in my program - to represent 3 variables in a row.

Code:

        struct Spring { 
               Vector equilPos; //represents equilibrium position of spring
               float k;         //spring coefficient - represents tightness - high value makes them more rigid
               float b;         //damping coefficient
               Spring(){
                        k=0;
                        b=0;
                        equilPos.zero();
               }
        };


class PhysObj {
    public:
//lots of unrelated functions / variables

           std::vector<Spring> springs;
           void add_spring(float springcoeff, float dampcoeff, float x, float y, float z);
//calculate forces (where the spring variables are actually used)
           void forces(const State &state, float t, Vector &force, Vector &torque);
 }


void PhysObj::add_spring(float springcoeff, float dampcoeff, float x, float y, float z){
     Spring* tempspring = new Spring;
     tempspring->equilPos.x = x;
     tempspring->equilPos.y = y;
     tempspring->equilPos.z = z;
     tempspring->k = springcoeff;
     tempspring->b = dampcoeff;
     springs.push_back(*tempspring);
     std::cout << "spring created, now "<< springs.size() << " spring, k=" 
          << springs[springs.size()-1].k << " b = "<< springs[springs.size()-1].b
          << std::endl;

}

void PhysObj::forces(const State &st, float t, Vector &force, Vector &torque) {
       //springs
       for (int i=0; i<springs.size(); i++){
           Vector dampingforce = springs[i].b * st.vel;
           force == (-springs[i].k) * st.pos - springs[i].equilPos)) - dampingforce;
       }
       std::cout << "Force: " << force.x << ",  " << force.y << ", " << force.z<< std::endl;
       std::cout << "Number of springs: " << springs.size() << std::endl;
}

The 'add_spring' function says there is 1 spring with the correct coefficients, the 'forces' function says there are 0 springs (and consequently, no forces).

Can someone help?