Question

我在这里有一些代码而且我正在努力解决它，因为我似乎无法掌握这个文件指针的东西。我很擅长处理文件。我已经看到了这样的其他问题，我尝试了适用于其他人的解决方案，但由于某种原因，他们不适合我。以下是问题所在代码的一部分：

    void writeRentals(char *filename, RentalT *allRentals, int totalRentals); 
int readRentals(char *filename, RentalT *allRentals);
void writeCars(char *filename, CarT *allCars, int totalCars);
int readCars(char *filename, CarT *allCars);

int main() {
    CarT allCars[255]; // a list of cars
    RentalT allRentals[255]; // a list of rentals
    int totalCars = 0; // number of all cars owned
    int totalRentals = 0; // number of rented cars
    int menu_choice, renterIndex, carId;
    char renterName[20], carMake[20];

    // read data from the files
    char rentalFilename[255];
    char carFilename[255];
    printf("Please enter the name of the rental records file:");
    fscanf("%s", &rentalFilename);
    printf("\nPlease enter the name of the car records file:");
    fscanf("%s", &carFilename);

    totalCars = readCars(carFilename, allCars);
    totalRentals = readRentals(&rentalFilename, allRentals);

这是我编译时遇到的错误：

 ----jGRASP exec: gcc -g -o carRental.exe carRental.c
carRental.c: In function 'main':
carRental.c:57:9: warning: passing argument 1 of 'fscanf' from incompatible pointer type [-Wincompatible-pointer-types]
  fscanf("%s", &rentalFilename);
         ^
In file included from carRental.c:1:0:
stdio.h:385:15: note: expected 'FILE * restrict {aka struct _iobuf * restrict}' but argument is of type 'char *'
   int __cdecl fscanf(FILE * __restrict__ _File,const char * __restrict__ _Format,...) __MINGW_ATTRIB_DEPRECATED_SEC_WARN;
               ^
carRental.c:57:15: warning: passing argument 2 of 'fscanf' from incompatible pointer type [-Wincompatible-pointer-types]
  fscanf("%s", &rentalFilename);
               ^
In file included from carRental.c:1:0:
stdio.h:385:15: note: expected 'const char * restrict' but argument is of type 'char (*)[255]'
   int __cdecl fscanf(FILE * __restrict__ _File,const char * __restrict__ _Format,...) __MINGW_ATTRIB_DEPRECATED_SEC_WARN;
               ^
carRental.c:59:9: warning: passing argument 1 of 'fscanf' from incompatible pointer type [-Wincompatible-pointer-types]
  fscanf("%s", &carFilename);
         ^
In file included from carRental.c:1:0:
stdio.h:385:15: note: expected 'FILE * restrict {aka struct _iobuf * restrict}' but argument is of type 'char *'
   int __cdecl fscanf(FILE * __restrict__ _File,const char * __restrict__ _Format,...) __MINGW_ATTRIB_DEPRECATED_SEC_WARN;
               ^
carRental.c:59:15: warning: passing argument 2 of 'fscanf' from incompatible pointer type [-Wincompatible-pointer-types]
  fscanf("%s", &carFilename);
               ^
In file included from carRental.c:1:0:
stdio.h:385:15: note: expected 'const char * restrict' but argument is of type 'char (*)[255]'
   int __cdecl fscanf(FILE * __restrict__ _File,const char * __restrict__ _Format,...) __MINGW_ATTRIB_DEPRECATED_SEC_WARN;
               ^


carRental.c:62:29: warning: passing argument 1 of 'readRentals' from incompatible pointer type [-Wincompatible-pointer-types]
  totalRentals = readRentals(&rentalFilename, allRentals);

非常感谢任何帮助，谢谢！

Answer 1

您已经搞砸了scanf和fscanf的使用情况。你错过了使用fscanf时传递的第一个参数。首先打开一个文件，然后将相应的文件指针作为第一个参数传递给fscanf。

使用scanf从控制台扫描字符串，如下所示。

printf("Please enter the name of the rental records file:");
scanf("%s", rentalFilename);
//No need of &rentalFile

然后使用文件指针打开此文件。

File *fp = fopen (rentalFilename, "r");//r for reading

然后您可以使用fscanf从文件中读取

fscanf(fp,"%s",line);//Note line is a char array
//This was just an example

您可能希望查看fscanf here的示例。

正如chux在评论中所建议的那样，探索在C中扫描字符串的各种方法.scanf的替代方法是gets（），fgets（）。看看哪个适合您的目的。避免使用弃用的方法。

遇到fscanf文件指针错误的问题

1 个答案: