树的括号表示法怎么写

#include
#include
#include
using namespace std;
struct treenode
{
char data;
treenode firstchild;
treenode *nextsibling;
};
treenode * creat_tree(char&a)
{ if((*a)==',')
{
a++;
}
if((*a)=='\0')
return NULL;
if((*a)==')')
{
a++;
return NULL;
}
if((*a)=='(')
{
a++;
}
treenode t=new treenode();
t->data=(a++);
t->firstchild=creat_tree(a);
t->nextsibling=creat_tree(a);
return t;
}
void show_tree(treenode *t)
{ //cout<<"123";
if(t==NULL)
return;
cout<data;
for(treenode *p=t->firstchild;p!=NULL;p=p->nextsibling)
{
show_tree(p);
}
}
int main()
{ //char ch[100];
char *a;//[100];
gets(a);
// puts(a);
treenode *t=creat_tree(a);
show_tree(t);
}

我写了一个，但又明显错误，希望大神能帮我改进。。

 #include<stdio.h>
#include<stdlib.h>
#include<memory.h>

typedef struct BiTNode {
    char data;
    struct BiTNode *lchild;
    struct BiTNode *rchild; 
} *BiTree;

BiTree CreateBiTree(BiTree T){
    char ch;
    scanf("%c",&ch);
    if (ch=='#'){ 
        return NULL; 
    }else {
        T = (BiTree)malloc(sizeof(struct BiTNode)) ;     
        T->data = ch;
        T->lchild=CreateBiTree(T->lchild);   
        T->rchild=CreateBiTree(T->rchild);    
        return T;
    }
}


void PreOrder(BiTree &T){
    if(T){                      
        printf("%c ",T->data);  
        PreOrder(T->lchild);   
        PreOrder(T->rchild);    
    }
}

void InOrder(BiTree &T){
    if(T){                     
        InOrder(T->lchild); 
        printf("%c ",T->data);  
        InOrder(T->rchild); 
    }
}

void PostOrder(BiTree &T){
    if(T){                     
        PostOrder(T->lchild);
        PostOrder(T->rchild);    
        printf("%c ",T->data);

    }
}

void ShowBiTree(BiTree  &bt)
{
    if (bt!=NULL){
        printf("%c",bt->data);
        if (bt->rchild!=NULL||bt->lchild!=NULL){
            printf("(");
            ShowBiTree(bt->lchild);
            if (bt->rchild!=NULL){
                printf(",");
            }
            ShowBiTree(bt->rchild);
            printf(")");
        }
    }
}

int main()
{
    printf("请依次输入字符: \n");
    BiTree T;
    T = CreateBiTree(T);
    printf("先序遍历: \n");
    PreOrder(T);
    printf("\n中序遍历: \n");
    InOrder(T);
    printf("\n后序遍历: \n");
    PostOrder(T);
    printf("\n用括号表示法输出二叉树:\n");
    ShowBiTree(T);
    printf("\n");
    system("pause");
    return 0;
}