Data read off disk problem

I have a problem. This code reads accurately the account names off disk, but not the balance. It just shows up as $0.00. Please tell me what the problem is.

Code:

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#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>

void addAccount(void);
void listAccounts(void);

struct account_data
{
      char name[60];
      double balance;
      struct entry
      {
              int check_num;
              char info[128];
              union
              {
                  double debit;
                  double credit;
              };
      };
};

int main()
{
        char c;
        int done = 0;
        char go;
        while(done == 0)
        {
                puts("\nDigital Checkbook\n");
                puts("A - Add new account\n");
                puts("L - List accounts\n");
                puts("Q - Quit\n");
                printf("Your choice: ");
               
                c = getchar();
                fflush(stdin);
                c = toupper(c);
                switch(c)
                {
                        case ('A'):
                                addAccount();
                                break;
                        case ('L'):
                                listAccounts();
                                break;
                        case ('Q'):
                                printf("\nAre you sure you want to quit? Y/N: ");
                                go = getchar();
                                go = toupper(go);
                                if(go == 'Y')
                                {
                                        done = 1;
                                        fflush(stdin);
                                        system("cls");
                                }
                                else if(go == 'N')
                                {
                                        fflush(stdin);
                                        system("cls");
                                }
                                break;
                        default:
                                puts("\nInvalid answer ");
                } /*End switch*/
        } /*End while*/
        return(0);
} /*End main()*/

void addAccount(void)
{
        FILE *Accounts;
        struct account_data account;
       
        printf("Enter account name: ");
        scanf("%s",&account.name);
        printf("How much money is currently in it? $");
        scanf("%f",&account.balance);
       
        Accounts = fopen("account.dat","a");
        if (Accounts == NULL)
        {
                puts("Error opening file");
                exit(1);
    }           
   
    fwrite(&account,sizeof(account),1,Accounts);
   
    fclose(Accounts);
    puts("Account added!");
    fflush(stdin);
}

void listAccounts(void)
{
        FILE *Accounts;
        struct account_data account;
        int x;
        Accounts = fopen("account.dat","r");
        if(Accounts == NULL)
        {
                puts("No data in file, or file not found.");
                return;
        }
       
        while(1 == 1)
        {
                x = fread(&account,sizeof(account),1,Accounts);
               
                if(x == 0) break;
               
                printf("\nAccount name:%s\n",account.name);
                printf("Balance: $%.2f\n",account.balance);
               
        }
        fclose(Accounts);
}

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That is the relevant part.

The problem is that it is not possible to read into a double variable with %f. Hence you won't get a valid result later when you try to write it or read it.

You can read into a double variable with %lf, though.

Thank you. And in Line 21, I get "warning: declaration does not declare anything". Huh?

Code:

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Accounts = fopen("account.dat","r");

---

should be

Code:

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Accounts = fopen("account.dat","r+b");

---

and you shoudl change

Code:

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        Accounts = fopen("account.dat","a");

---

as well

Which line is line 21?

Quote:

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And in Line 21, I get "warning: declaration does not declare anything". Huh?

---

Code:

---

struct entry
      {
              int check_num;
              char info[128];
              union
              {
                  double debit;
                  double credit;
              };
      };

---

You probably meant

Code:

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struct { /* ... */ } entry;

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which would actually declare a structure called entry inside of every account_data.

Also: cpwiki.sf.net/fflush

Thanks, but when there is a comma inserted in the monetary values, it does not interpret it correctly. Why?

Quote:

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Originally Posted by Sly

Thanks, but when there is a comma inserted in the monetary values, it does not interpret it correctly. Why?

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Why would it? Commas aren't part of valid numbers (unless you're in a locale where comma is the decimal separator)

How do I make it accept it?

You could write your own number-parsing code. Or you could strip all commas before you give sscanf() the string to convert to a number. (Which wouldn't be very robust.)

Or you could just say, "Enter the balance in dollars without commas"! :)

If you really want to allow commas, I'd write your own number parser. That way you could allow an optional '$' sign at the beginning of a number, ensure commas only occur at thousands separators, generate an error if more than two digits occur after the decimal point, etc.