Does this code meet the definition of recursion?

Question

I have a piece of code in which I doubt that this is an implementation of recursion by its definition. My understanding is that the code must call itself, the same function. I also doubt whether the code adds extra overhead to this code that can be seen with recursion. What are your thoughts?

class dhObject
{
public:
   dhObject** children;
   int numChildren;
   GLdouble linkLength; //ai 
   GLdouble theta; //angle of rot about the z axis
   GLdouble twist; //about the x axis
   GLdouble displacement; // displacement from the end point of prev along z
   GLdouble thetaMax;
   GLdouble thetaMin;
   GLdouble thetaInc;
   GLdouble direction;

   dhObject(ifstream &fin)
   {
      fin >> numChildren >> linkLength >> theta >> twist >> displacement >> thetaMax >> thetaMin;
      //std::cout << numChildren << std::endl;
      direction = 1;
      thetaInc = 1.0;
      if (numChildren > 0)
      {
         children = new dhObject*[numChildren];
         for(int i = 0; i < numChildren; ++i)
         {
            children[i] = new dhObject(fin);
         }
      }
   }

   void traverse(void)
   {
      glPushMatrix();
      //draw move initial and draw
      transform();
      draw();
      //draw children
      for(int i = 0; i < numChildren; ++i)
      {
         children[i]->traverse();
      }
      glPopMatrix();
   }

   void update(void)
   {
      //Update the animation, if it has finished all animation go backwards
      if (theta <= thetaMin)
      {
         thetaInc = 1.0;
      } else if (theta >= thetaMax)
      {
         thetaInc = -1.0;
      }
      theta += thetaInc;
      //std::cout << thetaMin << " " << theta << " " << thetaMax << std::endl;
      for(int i = 0; i < numChildren; ++i)
      {
         children[i]->update();
      }
   }

   void draw(void)
   {
      glPushMatrix();
      glColor3f (0.0f,0.0f,1.0f);
      glutSolidCube(0.1);
      glPopMatrix();
   }

   void transform(void)
   {
      //Move in the correct way, R, T, T, R
      glRotatef(theta, 0, 0, 1.0);
      glTranslatef(0,0,displacement);
      glTranslatef(linkLength, 0,0);
      glRotatef(twist, 1.0,0.0,0.0);
   }
};

Answer 1

Yes, because you have certain functions that call yourself. By definition, this is direct recursion. You can also have indirect recursion if you had a function A()calling function B(), a function B()in turn (directly or indirectly) calling function A()again.

Answer 2

/nitpicking. C:

void traverse( tree * t ) {
    if ( t != 0 ) {
        traverse( t->right );
        traverse( t->left );
    }
}

? , , . , . :

unsigned int f( unsigned int n ) {
    if ( n = 0 ) {
       return 0; 
    }
    else {
       return f( n - 1 );   // XXX
    }
}

, XXX, , , . , , .

Answer 3

traverse() update() , .

, :

• numChildren , , - .

• , .

• . , , .

Answer 4

, , , , , . , , 100 .

Answer 5

( ) . , . : .

The depth of the call stack is directly determined by the data structure on which the algorithm works.

What really happens is (pseudo-code):

Function Traverse(object o)
{
   [do something with o]

   Foreach(object child in o.Children)
       Traverse(child);

   [do something with o]
}