求二叉树节点所在层号

#include<stdio.h>
#include<stdlib.h>
#define NULL 0
#define MAXSIZE 100

typedef struct BTNode
{
    struct BTNode *lchild,*rchild;
    int data;
}BTNode,*btnode;

void createBtree(btnode &T)
{
    int t;
    scanf("%d",&t);
    if(t==0)
        T=NULL;
    else
    {
        T=(btnode)malloc(sizeof(BTNode));
        T->data=t;
        createBtree(T->lchild);
        createBtree(T->rchild);
    }
}

int L=1;

void leno(btnode &p,int key)
{
    if(p)
    {
        if(p->data==key)
            printf("leno=%d\n",L);
        ++L;
        leno(p->lchild,key);
        leno(p->rchild,key);
        --L;
    }
}

void main()
{
    btnode T;
    int key;
    createBtree(T);
    printf("input the element:\n");
    scanf("%d",&key);
    leno(T,key);
}