一个c++的数据结构问题，二叉树中关于建立二叉树的代码，请大虾们帮忙写一下，

//二叉树结点类型为字符型的情况
#include
#include
#include
#define null 0
#define MaxSize 1024
typedef struct tree
{ /*声明树的结构*/
struct tree *left; /*存放左子树的指针*/
struct tree *right; /*存放右子树的指针*/
char data; /*存放节点的内容*/
} treenode, * b_tree; /*声明二叉树的链表*/

b_tree Q[MaxSize];

/*建立二叉树，按完全二叉树的层次遍历序列输入*/
b_tree createbtree()
{
char ch;
int front,rear;
b_tree root,s;
root=NULL;
front=1;rear=0;
ch=getchar();
getchar();
while(ch!='?')
{
s=NULL;
if(ch!='.')
{
s=(b_tree)malloc(sizeof(treenode));
s->data=ch;
s->left=NULL;
s->right=NULL;
}
rear++;
Q[rear]=s;
if(rear==1)
root=s;
else
{
if(s&&Q[front])
if(rear%2==0)
Q[front]->left=s;
else
Q[front]->right=s;
if(rear%2==1)
front++;
}
ch=getchar();
getchar();
}
return root;
}

/*先序遍历打印二叉排序树*/
void preorder_btree(b_tree root)
{
b_tree p=root;
if(p!=null)
{
printf("%3c",p->data);
preorder_btree(p->left);
preorder_btree(p->right);
}
}

/* 中序遍历打印二叉排序树*/
void inorder_btree(b_tree root)
{
b_tree p=root;
if(p!=null){
inorder_btree(p->left );
printf("%3c",p->data );
inorder_btree(p->right );
}
}

/*后序遍历打印二叉排序树*/
void postorder_btree(b_tree root)
{
b_tree p=root;
if(p!=null)
{
postorder_btree(p->left );
postorder_btree(p->right );
printf("%3c",p->data );
}
}

/*求树的高度*/
int treedepth(b_tree bt)
{
int hl,hr,max;
if(bt!=null)
{
hl=treedepth(bt->left);
hr=treedepth(bt->right);
max=(hl>hr)?hl:hr;
return (max+1);
}
else
return 0;
}

int count=0;
/*求叶子结点总数*/
int leafcount(b_tree bt)
{
if(bt!=null)
{
leafcount(bt->left);
leafcount(bt->right);
if(bt->left==null&&bt->right==null)
count++;
}
return count;
}

void paintleaf(b_tree bt)
{
if(bt!=null)
{
if(bt->left==null&&bt->right==null)
printf("%3c",bt->data);
paintleaf(bt->left);
paintleaf(bt->right);
}
}

typedef b_tree ElemType ;

int main()
{
char nodelist[MaxSize];
int len,flag;
char cmd;
b_tree root;
do
{
printf(" 输入c......选择创建一棵二叉排序树\n");
printf(" 输入a......将结束本程序\n\n");
flag=0;
do
{
if(flag!=0)
printf("选择操作错误！请重新选择！\n");
fflush(stdin);
scanf("%c",&cmd);
flag++;
}while(cmd!='c'&&cmd!='a');
if(cmd=='c')
{
printf("请输入那你所要创建的二叉树的结点的值,以'？'结束）：\n");
getchar();
root=createbtree();
do
{
flag=0;
printf("\n\n 请选择你要对这棵二叉树所做的操作:\n\n");
printf(" x......先序遍历\n");
printf(" z......中序遍历\n");
printf(" h......后序遍历\n");
printf(" b......层次遍历\n");
printf(" d......求二叉树的深度\n");
printf(" y......求叶子总数并输出各叶子结点\n");
printf(" q......结束操作\n\n");
do
{
if(flag!=0)
printf("选择操作错误！请重新选择！\n");
fflush(stdin);
scanf("%c",&cmd);
flag++;
}while(cmd!='x'&&cmd!='z'&&cmd!='h'&&cmd!='b'&&cmd!='d'&&cmd!='y'&&cmd!='j'&&cmd!='q');
switch(cmd)
{
case 'x':
printf("\n先序遍历开始:\n");
preorder_btree(root);
printf("\n先序遍历结束\n\n");
break;
case 'z':
printf("\n中序遍历开始:\n");
inorder_btree(root);
printf("\n中序遍历结束\n\n");
break;
case 'h':
printf("\n后序遍历开始:\n");
postorder_btree(root);
printf("\n后序遍历结束\n\n");
break;

case 'd':
printf("\n这棵二叉树的高度：\n%d\n\n",treedepth(root));
break;
case 'y':
printf("\n这棵二叉树的叶子结点为：\n");
paintleaf(root);
printf("\n");
count=0;
count=leafcount(root);
printf("\n这棵二叉树的叶子总数为:\n%d\n\n",count);
count=0;
break;
}
}while(cmd!='q'&&cmd!='Q');
}
}while(cmd!='a'&&cmd!='A');
printf("****谢谢使用！欢迎指正！****\n\n");
return 0;
}

#include
#include
#include
struct tree
{
char info;
struct tree *left;
struct tree *right;
};
struct tree *root; /*树的第一个结点*/
struct tree *construct(struct tree *root, struct tree *r, char info);
void print(struct tree *r, int l);

int main(void)
{
char s[80];
root = NULL;
do
{
printf("Please input a character:");
gets(s);
root = construct(root,root,*s);
}while(*s);
print(root,0);
getch();
return 0;
}

struct tree *construct(
struct tree *root,
struct tree *r,
char info)
{
if(!r)
{
r = (struct tree *)malloc(sizeof(struct tree));
if(!r)
{
printf("内存分配失败！");
exit(0);
}
r->left = NULL;
r->right = NULL;
r->info = info;
if(!root)
return r;
if(info < root->info)
root->left = r;
else
root->right = r;
return r; /*是return r;还是return root;*/
}
if(info < r->info)
construct(r,r->left,info);
else
construct(r,r->right,info);
return root;
}

void print(struct tree *r, int l)
{
int i;
if(!r)
return;
print(r->left,l+1);
for(i = 0;i < l;++i)
printf(" ");
printf("%c\n",r->info);
print(r->right,l+1);
}

上面的是采用中序遍历，采用前序遍历和后序遍历的函数如下：
void scan(struct tree root)(前序遍历)
{
if(!root)return;
if(root->info);
执行相应操作;
scan(root->left);
scan(root->right);
}

void scan(struct tree root)(后序遍历)
{
if(!root)return;
scan(root->left);
scan(root->right);
if(root->info);
执行相应操作;
}