C 指针算术填充结构

Question

我目前正在尝试填充这样的结构

typedef struct
{
    int year;
    int month;
    int day;
    int hour;
    int minute;
} tDateTime;

typedef struct sFlight
{
    char code[MAX_NAME_LENGTH];
    char arrival[MAX_NAME_LENGTH];
    char departure[MAX_NAME_LENGTH];
    int availableSeats;
    tDateTime dateTime;
    struct sFlight * nextFlight;
} tFlight;

从 txt 文件中读取。这就是我目前正在做的事情

void ops_loadFlightsInformation(tFlight * firstFlight)
{   
    // Open the file with r to only read
    FILE *file = fopen(OPS_FLIGHTS_FILE, "r");
    // If file is not open return
    if(file == NULL) {
        return;
    }

    tFlight currentFlight;

    // Loop until there are no flights
    while(next != 0) {
        strcpy(currentFlight.code, helpers_scanFromFile(file, MAX_NAME_LENGTH));
        strcpy(currentFlight.departure, helpers_scanFromFile(file, MAX_NAME_LENGTH));
        strcpy(currentFlight.arrival, helpers_scanFromFile(file, MAX_NAME_LENGTH));
        fscanf(file, "%d\n", &currentFlight.availableSeats);
        fscanf(file, "%d/%02d/%02d %02d:%02d\n", &currentFlight.dateTime.year, &currentFlight.dateTime.month, &currentFlight.dateTime.day, &currentFlight.dateTime.hour, &currentFlight.dateTime.minute);
        fscanf(file, "%d\n", &next);

        printf("%s \n", currentFlight.code);
    }

    printf("%s \n", firstFlight->code);

    // Close the file handle
    fclose(file);
}

我无法思考如何填充 while 循环上的结构指针。我尝试了不同的方法，但最终总是得到

warning: X may be used uninitialized in this function

或者只是一遍又一遍地编辑同一个指针，因此只编辑第一个元素。循环工作正常 currentFlight 已正确填充，但我不知道如何将其转换为 firstFlight 结构和 ->nextFlight 指针

Answer 1

您想要读取航类并将其放入列表中。因此，在读取下一个航类之前，分配一 block 新的内存并将其放入 next 中。然后使用指针表示法来寻址成员:

void ops_loadFlightsInformation(tFlight * firstFlight)
{   
    // Open the file with r to only read
    FILE *file = fopen(OPS_FLIGHTS_FILE, "r");
    // If file is not open return
    if(file == NULL) {
        return;
    }

    tFlight *currentFlight = firstFlight;

    // Loop until there are no flights
    while(!feof(file)) {
        currentFlight->next= malloc(sizeof(tFlight));
        currentFlight= currentFlight->next;
        strcpy(currentFlight->code, helpers_scanFromFile(file, MAX_NAME_LENGTH));
        strcpy(currentFlight->departure, helpers_scanFromFile(file, MAX_NAME_LENGTH));
        strcpy(currentFlight->arrival, helpers_scanFromFile(file, MAX_NAME_LENGTH));
        fscanf(file, "%d\n", &currentFlight->availableSeats);
        fscanf(file, "%d/%02d/%02d %02d:%02d\n", &currentFlight->dateTime.year, &currentFlight->dateTime.month, &currentFlight->dateTime.day, &currentFlight->dateTime.hour, &currentFlight->dateTime.minute);
        //fscanf(file, "%d\n", &next);  // what is this?????

        printf("%s \n", currentFlight->code);
    }

    printf("%s \n", firstFlight->code);

    // Close the file handle
    fclose(file);
}

(注意:应添加 scanf 和 malloc 上的检查代码。假设您的助手是正确的并且始终读取字符串。假设文件至少包含一个航类。 )