二叉树按层遍历,该如何解决

#include<stdio.h>
#include<stdlib.h>
typedef  struct  btnode{
   char  data;
   struct btnode  *lchild, *rchild;
   }BTNode;
typedef struct{
   BTNode elem[20];
   int front,rear;
   }SqQueue;
BTNode * CreatTree( void );
void  Preorder(BTNode *bt );
void  Inorder(BTNode *bt );
void  Postorder(BTNode *bt );
void  Levelsorder(BTNode *bt);
void  ExChangeLeafs(BTNode *bt);
void  EnQueue(SqQueue *sq,BTNode *bt);
void  DelQueue(SqQueue *sq,BTNode *p);
void  InitQueue(SqQueue *sq);
main()
{
  BTNode *t;
  char s[10];
  for(;;)
  {
      printf("1--------CreatTree    2-----------Preorder  \n");
      printf("3--------Inorder      4-----------Postorder  \n");
      printf("5--------Levelsorder  6-----------ExchangeLeafs(Preorder)  \n");
      printf("7--------Exit\n");
      gets(s);
      switch(*s)
      {
        case '1':  t=CreatTree();
                   break;
    case '2':  Preorder(t);
                   printf("\n");
                   break;
        case '3':  Inorder(t);
                   printf("\n");
                   break;
        case '4':  Postorder(t);
                   printf("\n");
                   break;
    case '5':  Levelsorder(t);
                   printf("\n");
           break;
    case '6':  ExChangeLeafs(t);
                   Preorder(t);
                   printf("\n");
                   break;
        case '7':  printf("exit \n");
                   exit(0);
    }
  }
}
 #define  MAXNUM  20
 BTNode * CreatTree( void )
{     int i=1,j;char ch;
      BTNode *p[MAXNUM+1],*t,*s;
      t=NULL;
      printf("\n enter i,ch: \n");
      scanf("%d,%c",&i,&ch);
      while( i!=0 && ch!='#')
     {
       s=(BTNode *)malloc(sizeof(BTNode));
       s->data=ch;
       s->lchild=s->rchild=NULL;
       p[i]=s;
       if(i==1) t=s;
       else
      {
          j=i/2;
          if(i%2==0) p[j]->lchild=s;
          else p[j]->rchild=s;
       }
       scanf("%d,%c",&i,&ch);
      }
      ch=getchar();
      return t;
 }
void  Preorder(BTNode *bt )
{
     if (bt)
     {
       printf("%5c",bt->data);
       Preorder(bt->lchild);
       Preorder(bt->rchild);
      }
 }

void  Inorder(BTNode *bt )
{
    if (bt)
   {
    Inorder(bt->lchild);
    printf("%5c",bt->data);
    Inorder(bt->rchild);
    }
}

void  Postorder(BTNode *bt )
{
     if (bt)
     {
        Postorder(bt->lchild);
        Postorder(bt->rchild);
    printf("%5c",bt->data);
      }
 }
void ExChangeLeafs(BTNode *bt)
{
    BTNode *temp;
    if(bt)
    {
      temp=bt->lchild;
      bt->lchild=bt->rchild;
      bt->rchild=temp;
      ExChangeLeafs(bt->lchild);
      ExChangeLeafs(bt->rchild);
     }
}
void  Levelsorder(BTNode *bt)
{  BTNode p;
   SqQueue sq;
   InitQueue(&sq);
   EnQueue(&sq,bt);
   while(sq.front!=sq.rear)
  { DelQueue(&sq,&p);
    printf("%5c",p.data);
    if(p.lchild) EnQueue(&sq,p.lchild);
    if(p.rchild) EnQueue(&sq,p.rchild);
   }
}
void InitQueue(SqQueue *sq)
{
  sq->front=sq->rear=0;
}
void  EnQueue(SqQueue *sq ,BTNode *bt)
{ sq->elem[sq->rear]=*bt;
  sq->rear=(sq->rear+1)%20;
}
void  DelQueue(SqQueue *sq,BTNode *p)
{
   *p=sq->elem[sq->front];
   sq->front=(sq->front+1)%20;

}

------解决方案--------------------
用到队列  自己看吧

------解决方案--------------------
双向指针链表构建树 然后遍历

------解决方案--------------------