如果是单组数据可以改成这样

#include<stdio.h>
#include<stdlib.h>
struct treenode{
    char data;
    struct treenode *left;
    struct treenode *right;
};
void func(struct treenode *root);
struct treenode *creat();
int flag = 0;//结束标记
int main(){

	struct treenode *root = creat();
    func(root);

}
struct treenode *creat(){
    char s;
    if (flag) return NULL;
    scanf("%c",&s);
    if(s=='#'){
        return NULL;
        //TODO
    }
    if (s=='\n') {
        flag = 1;
        return NULL;
    }
    struct treenode *head = (struct treenode*)malloc(sizeof(struct treenode));
    head->data=s;
    head->left=creat();
    head->right=creat();
    return head;
};
void func(struct treenode *root){
    if(root==NULL){
        return;
        //TODO
    }
    func(root->left);
    printf("%c ",root->data);
    func(root->right);
}

但是这个题是多组数据输入，最好是先直接输入一行，然后处理，一行处理一次。