Problem on reading a binary file using fread function

Question

I am tasked to create an inventory program that stores data using structure and save the data into a binary file. The program should then be able to load the data i.e. the structure elements from the binary file. I am able to save the input data to a binary file using the fwrite function; however, I am having a problem in loading the file to the program using the fread function.

I already looked for similar problems but I can't find a similar case wherein the fread is used to pass the structure elements saved to the structure variable in the program.

This is the code for my structure

struct details {
    char name[30];
    double price;
    int code;
    int qty;
};

details item[SIZE];

Function in adding an item to the inventory

int AddItem(int n){
    details inputitem;
    printheader();
    printf("Item Name: ");
    scanf("%s", inputitem.name); //check %[^\n]
    printf("\nItem Price: ");
    scanf("%lf", &inputitem.price);
    printf("\nItem Code: ");
    scanf("%d", &inputitem.code);
    printf("\nQuantity: ");
    scanf("%d", &inputitem.qty);
    printf("\nItem Added! The ID of the item is %d.\n", n+1);
    item[n] = inputitem;
}

Function in displaying the inventory

int DisplayInventory(int n){
    printheader();
    printf("ID |    NAME           |   CODE   |  QUANTITY |  PRICE \n");
    printf("------------------------------------------------------------\n");
    for(int i=0; i<n; i++){
        printf("%d   %-18s   %-10d  %-10d  %-10lf \n",i+1,item[i].name,item[i].code,item[i].qty,item[i].price);
    }
}

Function in saving to a binary file

int SaveFile(int n){
    FILE *fp;
     fp=fopen("C:\\Users\\Royce\\Documents\\CPEPROG2 Goden Final Project\\Inventory.txt","wb");

      if(!fp) {
             printf("Cannot open file.\n");
             system("pause");
             exit(1);
      }


      for(int i=0; i<n; i++){
          fwrite(&item[i], sizeof(struct details), 1, fp);
      }



      fclose(fp);
      printf("File is saved!\n");

}

Function in loading the binary file

int LoadFile(int n){
     FILE *fp;
     fp=fopen("C:\\Users\\Royce\\Documents\\CPEPROG2 Goden Final Project\\Inventory.txt","rb");

      if(!fp) {
             printf("Cannot open file.\n");
             system("pause");
             exit(1);
      }


      struct details inputitem;
      int i = 0;
      while(fread(&inputitem, sizeof(struct details),1, fp)){

           item[i] = inputitem; 

           i++;
/*    printf("%d   %-18s   %-10d  %-10d  %-10lf \n",i+1,item[i].name,item[i].code,item[i].qty,item[i].price); */

      }
      fclose(fp);

      printf("File is loaded!\n");  
}

I expect the program to show in the DisplayInventory function the details of the structure saved in the binary file. However, nothing shows up at all.

When i try to print the structure in the LoadFile function (using the commented line), all variables show 0.

EDIT Main Function

int main (){



    int choice; //gets the choice of user from the menu
    bool condition = 1; //loops the menu
    //details item[50]; 
    int count=0; //counts the number of items in the inventory

    do{
        printheader(); //prints the title of the program
        printmenu(); //prints the menu (list of commands)
        scanf("%d", &choice);
        switch(choice){
            case 1: system("cls");
                    AddItem(count);
                    count++; 
                    system("PAUSE"); 
                    system("cls");
                    break;
            case 2: system("cls");
                    //EditItem();
                    system("PAUSE"); 
                    system("cls");
                    break;
            case 3: system("cls");
                    //DeleteItem();
                    system("PAUSE"); 
                    system("cls");
                    break;          
            case 4: system("cls");
                    //ViewItem();
                    system("PAUSE"); 
                    system("cls");
                    break;  
            case 5: system("cls");
                    DisplayInventory(count);
                    system("PAUSE"); 
                    system("cls");
                    break;
            case 6: system("cls");
                    SaveFile(count);
                    system("PAUSE"); 
                    system("cls");
                    break;
            case 7: system("cls");
                    LoadFile(count);
                    system("PAUSE"); 
                    system("cls");
                    break;
            case 8: printf("\nThank you!");
                    exit(0);
                    break;
            default: printf("\nInvalid Input!\n");  
                     getch();
                     system("cls");     

        }
    }while(condition = 1);


    return 0;
}

The LoadFile() function does not return any value. Should it be i the number of records? Please take note of compiler warnings, which should also expose the missing function return value in all the other functions posted here. — Weather Vane
– Weather Vane, Commented Jul 1, 2019 at 18:32
details item[SIZE]; it won't compile because of missing keyword struct, are you sure you have given the right code? — kiran Biradar
– kiran Biradar, Commented Jul 1, 2019 at 18:36
The values of the fields got printed when i put it before the i++ line. However, i still can't "load" them in the DisplayInventory function. I don't get it. Shouldn't the item[] structure array be updated in the load function since item[] is a global variable? — Hexyzroyce
– Hexyzroyce, Commented Jul 2, 2019 at 6:52
Also about the function return value, should functions always return a value even if they're not void? I use int functions because I need to pass the value of the number of records from the main function to the functions. I didn't add a return value because well I did not need to return any value to the main function. Please correct me if I'm wrong, I'm not really that good in programming yet. Thanks! — Hexyzroyce
– Hexyzroyce, Commented Jul 2, 2019 at 6:57

Dali · Accepted Answer · 2019-07-02 14:43:30Z

0

The program never increments the 'count' variable, so when 'DisplayInventory' is called the value is always 0 and nothing is displayed :

return the i variable in 'LoadFile()' and assign it to the 'count' variable in the main() scope : in LoadFile :

    ...
    printf("File is loaded!\n");  
    return i;
}

in main :

...
case 7: system("cls");
    count = LoadFile(count);
    system("PAUSE"); 
    system("cls");

Note that the 'n' argument in 'int LoadFile(int n)' is not used, you could remove it.

answered Jul 2, 2019 at 14:43

Dali

3441 silver badge11 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Problem on reading a binary file using fread function

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related