无法从用户读取字符 [英] can not read character from user

问题描述

在这段代码中，我正在创建一个二叉树，直到用户需要节点数.但是在从用户那里获取输入时，它在某处失败了..

here in this code i am creating a binary tree until user wants number of nodes. but while getting input from user it fails somewhere..

   struct node *createTree(struct node *root)
{
  int n;
  char ch;
  struct node *t1;
  t1=(struct node *)malloc(sizeof(struct node));
  printf("Enter Element\n");
  scanf("%d",&n);
  if(root==NULL)
    {
  t1->data=n;
  t1->left=NULL;
  t1->right=NULL;
  root=t1;
    } 

  printf("do you want to add node at left?\n");

这不能正常工作

scanf("%c",&ch);

scanf("%c",&ch);

  if(ch=='y')
    {
      t1->left=createTree(t1->left);

    }


   printf("do you want to add node at right?\n");
   scanf("%c",&ch);

   if(ch=='y')
    {
      t1->right=createTree(t1->right);

    }




  return root;



}

推荐答案

这样做:

printf("do you want to add node at right??!\n");
scanf("%c",&ch);
while (getchar()!='\n');  //<-- eat up trailing newline chars - Reads all characters of the line until the end of line is found.

当您在输入键盘输入后按 Enter 键时 - 缓冲区中会保留一个尾随换行符，下次调用 scanf 时会读取该换行符.

When you press enter after entering a keyboard input - there stays in the buffer a trailing newline character which the next call on scanf reads.

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