c - 在链表中输入元素时进行迭代

Question

这个问题已经有答案了:

c program doesn't work scanf char (2 个回答)

已关闭 6 年前。

我正在尝试用C语言制作一个简单的链表。但是程序只是跳过“输入更多节点？[y/n]”部分的输入。这是我的程序:

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

struct node{
    int data;
    struct node *next;
}*start = NULL;

void createlist()
{
    int item;
    char choice = 'y';

    struct node *newNode;
    struct node *current;

    while(choice != 'n')
    {
        printf("Enter item to add in the Linked List\n\n");
        scanf("%d", &item);

        newNode = (struct node *)malloc(sizeof(struct node));

        newNode->data = item;
        newNode->next = NULL;

        if(start == NULL)
        {
            start = newNode;
            current = newNode;
        }
        else
        {
            current->next = newNode;
            current = newNode;
        }

        printf("Enter more nodes?[y/n]\n");
        scanf("%c", &choice);
    }
}

void display()
{
    struct node *new_node;
    printf("Your node is :\n");
    new_node = start;
    while(new_node!=NULL)
    {
        printf("%d ---> ", new_node->data );
        new_node = new_node->next;

    }
}

int main()
{
    createlist();
    display();
    return 0;
}

输出: Program skipping choice input part

但是当我将 choice 变量从 char 更改为 int 时，程序运行完美。这是工作函数:

void createlist()
{
    int item;
    int choice = 1;

    struct node *newNode;
    struct node *current;

    while(choice != 0)
    {
        printf("Enter item to add in the Linked List\n\n");
        scanf("%d", &item);

        newNode = (struct node *)malloc(sizeof(struct node));

        newNode->data = item;
        newNode->next = NULL;

        if(start == NULL)
        {
            start = newNode;
            current = newNode;
        }
        else
        {
            current->next = newNode;
            current = newNode;
        }

        printf("Enter more nodes?\n[NO - 0, YES - 1]\n");
        scanf("%d", &choice);
    }
}

你们能告诉我为什么当choice是char类型时程序无法正常工作吗？

Answer 1

输入缓冲区中有一个换行符，正在以%c 格式读取。改变

scanf("%c", &choice);

至

scanf(" %c", &choice);`

前导空格告诉 scanf 首先清除空格。使用 %d 格式时会自动发生。