恳请高手指点一下，这个循环怎么不行呢！

const int snum=9;
for (int i=1;i<snum;i++)
{
     
        snakelink[i].length = slength;//每节蛇的长度
                   snakelink[i].radius= sradius;//半径

        snakelink[i].mass   = smass;//质量
        snakelink[i].body = dBodyCreate(world);
        dMassSetZero(&m1);

      dsSetColor(0.0,1.0,0.0);
      dsDrawCylinder(dBodyGetPosition(snakelink[i-1].body),dBodyGetRotation(snakelink[i-1].body),snakelink[i].length,snakelink[i].radius);
   
      
        dMassSetCylinderTotal(&m1,snakelink[i].mass,1,snakelink[i].radius, snakelink[i].length);
        
        dMassSetBoxTotal(&m1,snakelink[i].mass,snakelink[i].length, snakelink[i].radius,snakelink[i].radius);
   
   

}