无法将双数正确导入到 C 程序中

Question

我有一个这样格式化的txt文件:

MyDepartureTown MyDestinationTown 123.45 Vehicle 12

我正在尝试将数据导入到我的 C 程序中。这是我用来实现这一目标的代码:

void import_city_info(Grafo *G)
{
    char city_dep[20];
    char city_des[20];
    double km;
    char vehicle[12];
    int time;

    FILE *data_file = fopen("data/routes.txt", "r");
    if (data_file == NULL)
    {
        fprintf(stderr, "Errore. Impossibile aprire il file.\n");
        exit(EXIT_FAILURE);
    }

    while (5 == fscanf(data_file, "%s %s %f %s %d", &city_dep, &city_des, &km, &vehicle, &time))
    {
        printf("%2.3f\n", km);
        //more code...

    }
}

当我尝试打印双数时，它输出0.00。它实际上正确导入了除 double 据之外的所有数据。我做错了什么？

Answer 1

您使用了错误的说明符来读取double。这将调用未定义的行为。您需要%lf。

while (5 == fscanf(data_file, "%s %s %lf %s %d", &city_dep, &city_des, &km, &vehicle, &time))
{