二叉树的创建及其遍历

编译的时候总是出现这个错误：[Error] ld returned 1 exit status

哪位大神帮忙看看！！！


#define _CRT_SECURE_NO_WARNINGS
#include "stdio.h"
#include "malloc.h"
#include "stdlib.h"
#define OK 1
#define ERROR 0
#define  OVERFLOW -2
typedef int Status;
typedef char ElemType;
typedef struct BTNode
{
    ElemType data;
    struct BTNode *lchild,*rchild;
}BTNode,*BTree;

Status CreatBtree(BTree *T);
Status PreOrderTraverse_Recursive(BTree T,Status(*Visit)(ElemType e));
Status InOrderTraverse_Recursive(BTree T,Status(*Visit)(ElemType e));
Status PostOrderTraverse_Recursive(BTree T,Status(*Visit)(ElemType e));
Status PrintElement(ElemType e);

Status CreatBtree(BTree *T)
{
    char ch;
    scanf("%c",&ch);
    if(ch==' ')
    {
        (*T)=NULL;
    }
    else
    {
        if(!((*T)=(BTree)malloc(sizeof(BTNode))))
        exit(OVERFLOW);
        (*T)->data=ch;
        CreatBTree(&((*T)->lchild));
        CreatBTree(&((*T)->rchild));
    }
        return OK;
        
}
Status PreOrderTraverse_Recursive(BTree T,Status(*Visit)(ElemType e))
{
    if(T)
    {
        if(Visit(T->data));
        if(PreOrderTraverse_Recursive(T->lchild,Visit))
        if(PreOrderTraverse_Recursive(T->rchild,Visit))
        return OK;
        return ERROR;
    }
    else
    {
        return OK;
    }
}
Status InOrderTraverse_Recursive(BTree T,Status(*Visit)(ElemType e))
{
if(T)
    {
        if(InOrderTraverse_Recursive(T->lchild,Visit))
        if(Visit(T->data));
        if(InOrderTraverse_Recursive(T->rchild,Visit))
        return OK;
        return ERROR;
    }
    else
    {
        return OK;
    }
}
Status PostOrderTraverse_Recursive(BTree T,Status(*Visit)(ElemType e))
{
if(T)
    {
        if(PostOrderTraverse_Recursive(T->lchild,Visit))
        if(PostOrderTraverse_Recursive(T->rchild,Visit))
        if(Visit(T->data));
        return OK;
        return ERROR;
    }
    else
    {
        return OK;
    }
}
Status PrintElement(ElemType e)
{
    putchar(e);
    return OK;
}
int main()
{
    BTree T;
    CreatBTree(&T);
    PreOrderTraverse_Recursive(T,PrintElement);
    putchar('\n');
    InOrderTraverse_Recursive(T,PrintElement);
    putchar('\n');
    PostOrderTraverse_Recursive(T,PrintElement);
    putchar('\n');
    return 0;
}