输入中序、后序遍历顺序，输出先序遍历顺序，求解有什么问题

constructBitree(char pPost,char *pMid,int iLen)
{
int iPos=0;
char *p;
if(iLen<=0)
return NULL;
BiTree *pNode=(BiTree)malloc(sizeof(BiTNode));
pNode->data=pPost(pPost+iLen-1);
for (p=pMid;p {
if(*p==*(pPost+iLen-1))
break;
}
iPos=p-pMid;
pNode->lchild=constructBitree(pPost,pMid,iPos);
pNode->rchild=constructBitree(pPost+iPos,pMid+iPos+1,iLen-1-iPos);
return pNode;
}