c++ crashes using frameworks, bad constructor - c++

Question

I am writing a simple animation to draw a ball bouncing off walls. Here is the class:
class Ball{
private:
int x,y; //position
int vx,vy; //velocity
int rad=20; //radius
ofColor color; //color
public:
Ball(int a, int b, int c, int d,ofColor e);
Ball();
void draw();
void move();
};
When I construct Ball with 5 arguments everything works fine, but it crashes when I use the one without arguments:
Ball::Ball(){
x=int(ofRandomWidth());
y=int(ofRandomHeight());
vx=int(ofRandom(-10,10));
vy=int(ofRandom(-10,10));
int r=int(ofRandom(0,255));
int g=int(ofRandom(0,255));
int b=int(ofRandom(0,255));
ofColor a(r,g,b);
color=a;
}
What can be wrong with this constructor?
ofRandom:
float ofRandom(float max) {
return max * rand() / (RAND_MAX + 1.0f);
}
//--------------------------------------------------
float ofRandom(float x, float y) {
float high = 0;
float low = 0;
float randNum = 0;
// if there is no range, return the value
if (x == y) return x; // float == ?, wise? epsilon?
high = MAX(x,y);
low = MIN(x,y);
randNum = low + ((high-low) * rand()/(RAND_MAX + 1.0));
return randNum;
}

Answer 1

You have to write the body of the null constructor i.e. Ball(). In this you are supposed to initialise all of your variables to some value which you will decide.
Otherwise these ints will have either garbage value or the default value 0.
Also color is an object of class ofColor right? So in the null constructor, you are supposed to initialize the value of color as well by calling its constructor in the constructor initializer list, like :
Ball(): color() or a parameterized constructor depending on what you wrote.
these are somethings that can be possible wrong with your constructor but since you havent posted the code I cant say.
Another thing is that you have initialized the variable rad inside the class. It is always good to initialize all variables in constructors, never in the class.