C链表在使用然后删除typedef语句后不再工作

我有一个程序在这里显示从输入的一天开始的一周的第二天。这不是一个实用或有效的程序，我只是用它来测试我学到的概念。它工作了一段时间，但在了解了typedef语句之后，我尝试在程序的结构“weekday”中使用它们来声明该类型的变量，但随后删除了typedef，因为它产生了错误（例如“不兼容的指针”和“不完整的定义”）。现在，即使我取出typedef语句，该文件仍显示错误。最奇怪的是，如果我将所有代码复制并粘贴到一个新文件中，错误就不会出现。有人知道是什么导致了这些错误吗

#include <stdio.h>
#include <stdbool.h>

    struct weekday {
        char *ptrday;
        struct weekday *next;
    };

void matchtest(char *eday, struct weekday *head, struct weekday *cursor) {
    cursor=head;
    bool equalstring=true;

    while (cursor!=NULL) {
        char *p=cursor->ptrday;
        equalstring=true;

        while (*eday!='\0') {
            if (*eday!=*p) {
                equalstring=false;
                break;
            }
            ++eday; ++p;
        }
        if (equalstring==1) {
            printf("The next day of the week is %s\n", cursor->next->ptrday);
            break;
        }
        cursor=cursor->next;
    }
    if (equalstring==false)
        printf("The next day of the week is Sunday\n");
}

int main (void) {
    char enteredday[80], *ptreday=enteredday;
    struct weekday sunday, monday, tuesday, wednesday, thursday, friday, saturday;
    struct weekday *head=&sunday;
    struct weekday *cursor=NULL;

    sunday.ptrday="Sunday"; monday.ptrday="Monday"; tuesday.ptrday="Tuesday";
        wednesday.ptrday="Wednesday"; thursday.ptrday="Thursday";
        friday.ptrday="Friday"; saturday.ptrday="Saturday";

    sunday.next=&monday; monday.next=&tuesday; tuesday.next=&wednesday;
        wednesday.next=&thursday; thursday.next=&friday; friday.next=&saturday;
        saturday.next=NULL;


    printf("This is a test for the next day of the week.\n\n");
    printf("Enter a day ");

    scanf("%s", enteredday);
    matchtest(ptreday, head, cursor);

    return 0;
}

#包括
#包括
结构工作日{
char*ptrday；
结构工作日*下一个；
};
无效匹配测试（char*eday，struct weekday*head，struct weekday*游标）{
光标=头部；
布尔相等字符串=真；
while（光标！=NULL）{
char*p=cursor->ptrday；
equalstring=true；
而（*eday！='\0'）{
如果（*eday！=*p）{
equalstring=false；
打破
}
++eday；++p；
}
if（equalstring==1）{
printf（“一周的第二天是%s\n”，光标->下一天->ptrday）；
打破
}
光标=光标->下一步；
}
if（equalstring==false）
printf（“一周的第二天是星期日”）；
}
内部主（空）{
字符输入日期[80]，*ptreday=输入日期；
结构工作日周日、周一、周二、周三、周四、周五、周六；
结构工作日*head=&sunday；
struct weekday*cursor=NULL；
sunday.ptrday=“sunday”周一.ptrday=“周一”周二.ptrday=“周二”；
星期三。ptrday=“星期三”；星期四。ptrday=“星期四”；
星期五。ptrday=“星期五”；星期六。ptrday=“星期六”；
星期日。下一个=&星期一；星期一。下一个=&星期二；星期二。下一个=&星期三；
周三。下一个=&周四；周四。下一个=&周五；周五。下一个=&周六；
星期六。下一个=空；
printf（“这是一周中第二天的测试。\n\n”）；
printf（“输入日期”）；
scanf（“%s”，输入日期）；
匹配测试（ptreday、head、cursor）；
返回0；
}

您遇到的一个问题是，您在comparator函数中修改了

eday

，但是如果比较失败，您无法将搜索设置为从字符串的开头开始，因为您不知道字符串从何处开始。这折磨着“星期四”，报告说“第二天”是星期天。对于其他一些测试，这是可行的。星期六之后的第二天被报道为星期天，因为混乱

您还有一个问题，周六后的第二天是未定义的

---

下面是合理的工作代码。我使用strcmp（）（因此也使用

）进行比较。我将

while（cursor！=NULL）

循环转换为

do{…}while（cursor！=head）循环，以便循环链表正常工作。我也会在读取时打印输入，然后再打印正式输出。这允许我使用
bash
的符号进行测试（
您会遇到什么错误？看起来您需要删除旧的对象文件并重新编译以获得新的文件。故事的一个寓意是“使用VCS”（版本控制系统）。一旦您做出的更改破坏了某些正在工作的内容，就应该确保您在VCS中有工作代码，以便您可以恢复工作代码并将工作代码与损坏的代码进行比较。奇怪的是，星期日不是星期六之后的第二天。您的代码不能正确处理其他日期作为条目（如果给出的名称不是一周中某一天的名称，则不会报告问题）。代码在我的电脑上运行正常。看起来@Dayalrai是正确的。
#include <stdio.h>
#include <string.h>

struct weekday
{
    char *ptrday;
    struct weekday *next;
};

static void matchtest(char *eday, struct weekday *head)
{
    struct weekday *cursor = head;

    do
    {
        if (strcmp(eday, cursor->ptrday) == 0)
        {
            printf("The next day of the week after %s is %s\n", eday, cursor->next->ptrday);
            return;
        }
        cursor = cursor->next;
    } while (cursor != head);

    printf("The 'day of the week' %s does not match any day of the week!\n", eday);
}

int main(void)
{
    char enteredday[80];
    struct weekday sunday, monday, tuesday, wednesday, thursday, friday, saturday;
    struct weekday *head = &sunday;

    sunday.ptrday = "Sunday";
    monday.ptrday = "Monday";
    tuesday.ptrday = "Tuesday";
    wednesday.ptrday = "Wednesday";
    thursday.ptrday = "Thursday";
    friday.ptrday = "Friday";
    saturday.ptrday = "Saturday";

    sunday.next = &monday;
    monday.next = &tuesday;
    tuesday.next = &wednesday;
    wednesday.next = &thursday;
    thursday.next = &friday;
    friday.next = &saturday;
    saturday.next = &sunday;

    printf("This is a test for the next day of the week.\n\n");
    printf("Enter a day ");

    if (scanf("%79s", enteredday) == 1)
    {
        printf("Got: [%s]\n", enteredday);
        matchtest(enteredday, head);
    }

    return 0;
}

$ for d in Sunday Monday Tuesday Wednesday Thursday Friday Saturday Otherday; do ./nwd <<< $d; done
This is a test for the next day of the week.

Enter a day Got: [Sunday]
The next day of the week after Sunday is Monday
This is a test for the next day of the week.

Enter a day Got: [Monday]
The next day of the week after Monday is Tuesday
This is a test for the next day of the week.

Enter a day Got: [Tuesday]
The next day of the week after Tuesday is Wednesday
This is a test for the next day of the week.

Enter a day Got: [Wednesday]
The next day of the week after Wednesday is Thursday
This is a test for the next day of the week.

Enter a day Got: [Thursday]
The next day of the week after Thursday is Friday
This is a test for the next day of the week.

Enter a day Got: [Friday]
The next day of the week after Friday is Saturday
This is a test for the next day of the week.

Enter a day Got: [Saturday]
The next day of the week after Saturday is Sunday
This is a test for the next day of the week.

Enter a day Got: [Otherday]
The 'day of the week' Otherday does not match any day of the week!
$

#include <stdio.h>
#include <string.h>

typedef struct Weekday Weekday;
struct Weekday
{
    char *ptrday;
    Weekday *next;
};

Weekday days_of_the_week[7] =
{
    { "Sunday",    &days_of_the_week[1] },
    { "Monday",    &days_of_the_week[2] },
    { "Tuesday",   &days_of_the_week[3] },
    { "Wednesday", &days_of_the_week[4] },
    { "Thursday",  &days_of_the_week[5] },
    { "Friday",    &days_of_the_week[6] },
    { "Saturday",  &days_of_the_week[0] },
};

static void matchtest(char *eday, Weekday *head)
{
    Weekday *cursor = head;

    do
    {
        if (strcmp(eday, cursor->ptrday) == 0)
        {
            printf("The next day of the week after %s is %s\n", eday, cursor->next->ptrday);
            return;
        }
        cursor = cursor->next;
    } while (cursor != head);

    printf("The 'day of the week' %s does not match any day of the week!\n", eday);
}

int main(void)
{
    char enteredday[80];

    printf("This is a test for the next day of the week.\n\n");
    printf("Enter a day ");

    if (scanf("%79s", enteredday) == 1)
    {
        printf("Got: [%s]\n", enteredday);
        matchtest(enteredday, days_of_the_week);
    }

    return 0;
}