Help on C File Handling

[cold_fusion]

---

Your write routine has the problem. You need to fseek every write.

		printf("\nEnter no. ");
		scanf("%d",&x);
		printf("\nEnter name: ");
		scanf("%s",&st);
		strcpy(my_data[x-1].name,st);
		printf("\nOwes? ");
		scanf("%f",&owe);
		my_data[x-1].owes=owe;
		printf("\nWRITER");
		
		/* randomly move pointer to the right record position to write */
		fseek(file_pointer, (x-1) * sizeof(struct entry), SEEK_SET );
		fwrite(&my_data[x-1],sizeof(struct entry),1,file_pointer);

Your original read routine works also with this modification on the write routine.

[GuyVeR]

I wrote your code.
It still doesn't work.

[cold_fusion]

Delete writer.dat and test again. I recompiled the code with my modification and works OK.
I use gcc, not turbo C, but this does not matter anyway for both supports ANSI.

Be sure also to input 5 records and nos. 1,2,3,4,5 complete. And put back your original read routine (w/o fseek).

#include <stdio.h>
#include <string.h>
#define INDEX 5

#define getch getchar
#define clrscr()

struct entry{
    char name[20];
    float owes;
    }my_data[INDEX];

main()
{
char letra;
int x;
for(x=0;x<INDEX;x++)
    {
    my_data[x].owes=0;
    }
do
{
clrscr();
printf("\nW-rite  R-ead  Q-uit");
letra=getch();
switch(toupper(letra))
    {
    case('W'):
        writer();
        break;
    case('R'):
        reader();
        break;
    case('Q'):
        break;
    }
}while((toupper(letra))!='Q');
}

writer()
{
int x;
float owe;
char st[20];
    FILE *file_pointer;
    if((file_pointer=fopen("writer.dat","a"))!=NULL)
        {
        printf("\nEnter no. ");
        scanf("%d",&x);
        printf("\nEnter name: ");
        scanf("%s",&st);
        strcpy(my_data[x-1].name,st);
        printf("\nOwes? ");
        scanf("%f",&owe);
        my_data[x-1].owes=owe;
        printf("\nWRITER");

        /* randomly move pointer to the right record position to write */
        fseek(file_pointer, (x-1) * sizeof(struct entry), SEEK_SET );
        fwrite(&my_data[x-1],sizeof(struct entry),1,file_pointer);

        }
    else printf("Error writing writer.dat\n");
    fclose(file_pointer);
    getch();
}

reader()
{
    FILE *file_pointer;
    struct entry buffer[INDEX];
    int x;
    if((file_pointer=fopen("writer.dat","r"))==NULL)
        {
        printf("Error reading writer.dat\n");
        }
    else
        {
        printf("\nOwes: ");
        rewind(file_pointer);
        fread(my_data,sizeof(struct entry),INDEX,file_pointer);
        for(x=0;x<INDEX;x++)
            {
            printf("\nRecord %d %3.2f",x,my_data[x].owes);
            }
        fclose(file_pointer);
        }
    getch();
    return(0);
}

[GuyVeR]

YES!!! IT WORKS!!! IT WORKS!!!
Thank you very much.
Now, I have a sample for this type of problem. I really had a hard time looking for a demonstration of the fread, fwrite, and fseek function. Thank you so much.
I'll just post again if ever I have a question. Thank you very much for helping me.

[cold_fusion]

You are welcome!
Glad to hear that it worked.