BTree Unite(BTree T,BTree p,BTree y)   /* 结点合并 */
{BTree t,l,ap,last;
int u,v,w,j,a,finish,s,i;
Book x;
t=p->parent;
u=1+p->keynum;
if(t->keynum==0)
{T=y;T->parent->keynum=0;} /* 如果父亲结点为空，则将合并后的结点改为根结点 */
else
{if(p->keynum!=0)
      v=Search(t,p->key[p->keynum].key);
  else 
      v=Search(t,y->key[y->keynum].key);
  if(v!=0)
    {l=t->ptr[v-1];
     w=l->keynum;
     l->key[l->keynum+1]=t->key[v];
     l->keynum+=1;
     for(j=l->keynum+1;j<=l->keynum+p->keynum;j++)
          l->key[j]=p->key[j-l->keynum];
     l->keynum=l->keynum+p->keynum;
     for(j=w+1;j<=w+u;j++)
        {l->ptr[j]=y;
        y->parent=l;
        l->ptr[j]->parent=l;}
    for(j=v;j<t->keynum;j++)
        {t->key[j]=t->key[j+1];
        t->ptr[j]=t->ptr[j+1];
        t->ptr[j]->parent=t;}
    t->keynum-=1;
    if(l->keynum>=m)
           {finish=FALSE;
            ap=(BTree)malloc(sizeof(BTNode));
            ap->parent=NULL;
            ap->keynum=0;
            while(l->keynum!=0&&finish==FALSE)
                 {s=(m+1)/2;
                  x=l->key[s];
                  ap=split(l,ap);
                  last=l;
                  l=l->parent;
                  if(l->keynum!=0)
                  {i=Search(l,x.key);
                   l=Insert(l,i,x,ap);}
                  if(l->keynum<m&&l->keynum!=0)
                  {finish=TRUE;
                   l=last;}
                 }
              if(finish==FALSE)
              {T=Newroot(last,x,ap);l=T;}}
      if(t->keynum==0)  T=Unite(T,t,l);}
  else
    {l=t->ptr[1];
     for(j=l->keynum+1+p->keynum;j>1+p->keynum;j--)
        {l->key[j]=l->key[j-1-p->keynum];
          l->ptr[j]=l->ptr[j-1-p->keynum];
          l->ptr[j]->parent=l;}
     l->ptr[1+p->keynum]=l->ptr[0];
     l->ptr[1+p->keynum]->parent=l;
     for(j=1;j<=p->keynum;j++)
        l->key[j]=p->key[j];
     l->key[1+p->keynum]=t->key[1];
     for(j=0;j<1+p->keynum;j++)
          {l->ptr[j]=y;
          y->parent=l;
          l->ptr[j]->parent=l;}
      l->keynum=l->keynum+1+p->keynum;
      for(j=1;j<t->keynum;j++)
        {t->key[j]=t->key[j+1];
        t->ptr[j]=t->ptr[j+1];
        t->ptr[j]->parent=t;}
      t->keynum-=1;
      if(l->keynum>=m)
           {finish=FALSE;
            ap=(BTree)malloc(sizeof(BTNode));
            ap->parent=NULL;
            ap->keynum=0;
            while(l->keynum!=0&&finish==FALSE)
                 {s=(m+1)/2;
                  x=l->key[s];
                  ap=split(l,ap);
                  last=l;
                  l=l->parent;
                  if(l->keynum!=0)
                  {i=Search(l,x.key);
                   l=Insert(l,i,x,ap);}
                  if(l->keynum<m&&l->keynum!=0)
                  {finish=TRUE;
                   l=last;}
                 }
              if(finish==FALSE)
              {T=Newroot(last,x,ap);l=T;}
           }
      if(t->keynum==0)
          T=Unite(T,t,l);
      else
        {t->ptr[0]=l;
         t->ptr[0]->parent=t;}
     }
}
return(T);
}


先谢谢了..从别的地方拷的,完全看不懂的说,请高手在关键的地方给加点注释.急用..再次感谢..