Question

我正在加载文件：

05 11 2014 14 53 00
AB01 52.408 -4.217
XY23 51.750 -4.300
PQ29 52.100 -6.000
NY23 52.000 -5.900

第一行被放入dateTime结构中。然后我的代码应该遍历其余的行，将它们放入一个链接的结构列表中。但是，它会在无限循环中创建相同元素的链接列表。

typedef struct observer{
    char id[21];
    float lat;
    float longitude;
    struct observer *next;
} observer;

printf("Please enter the name of the observer file: ");
    scanf("%s", fileName);
    FILE* f1 = fopen(fileName, "r");
    if(f1 == NULL)
    {
        perror("Error opening file");
        return;
    }
    fscanf(f1, "%d %d %d %d %d %d", &dateTime.date, &dateTime.month, 
            &dateTime.year, &dateTime.hour, &dateTime.minute, &dateTime.second);
    while(fscanf(f1, "%s %f %f", temp_id, &temp_lat, &temp_long))
    {
        struct observer *new_obs = make_observer(temp_id, temp_lat, temp_long);
        insert_observer(new_obs, &observer_start);
        print_observer(&observer_start);
    }
    fclose(f1);

observer* make_observer(char *id, float lat, float longitude)
{
    observer *node = (observer*) malloc(sizeof(observer));
    strcpy(node->id, id);
    node->lat = lat;
    node->longitude = longitude;
    node->next = NULL;
    return node;
}

void insert_observer(observer *node, observer **list)
{
    observer *current;
    observer *previous = NULL;
    //int inserted = 0;

    if(*list == 0)
    {
        *list = node;
        return;
    }

    current = *list;
    while(current != NULL)
    {
        if(previous != NULL)
        {
            previous->next = node;
        }
        else
        {
            *list = node;
        }
        previous = current;
        current = current->next;
    }

}

Answer 1

尝试将插入功能更改为：

void insert_observer(observer *node, observer **list)
{
    if (*list)
    {
        observer *current = *list;
        observer *previous;
        while (current)
        {
            previous = current;
            current = current->next;
        }
        previous->next = node;
    }
    else
        *list = node;
}

这只是查找列表的结尾并将节点附加到最后一个列表项。

您还需要更改主循环while条件以检查是否已读取预期的字段数：

while (fscanf(f1, "%s %f %f", temp_id, &temp_lat, &temp_long) == 3)

C为什么循环第一项？

1 个答案: