Ive been trying to understand the below code for a while and need to know if it "acts like a record" for a single user. At the end users[userdb] is like an array for 6 struct user records?
#define userdb 5
/* DataBase*/
struct user
{char username[10];
char userid[9];
char password[4] ;
}users[userdb];
I need to have a simple database that stores 5 records that contain the name id and pass of 5 different users. And then write search or over write certain records and or a field within that record.
I have very little knowlege on how any of this type of stuff works but ive been researching and found a program that does pretty much what i want to do with my struct but it does it with a single variable the code is below. i placed sleep statements to see what it does.
#include<stdio.h>
#include<stdlib.h>
#include<conio.h>
#include<string.h>
#include<dos.h>
#include<math.h>
#include<ctype.h>
/* random record description - could be anything */
struct rec
{
int x,y,z;
};
/* writes and then reads 10 arbitrary records from the file "junk". */
void main()
{
int i,j;
FILE *f;
struct rec r;
/* create the file of 10 records */
f=fopen("junk","w");
for (i=1;i<=10; i++)
{
r.x=i;
fwrite(&r,sizeof(struct rec),1,f);
}
fclose(f);
/* read the 10 records */
f=fopen("junk","r");
for (i=1;i<=10; i++)
{
fread(&r,sizeof(struct rec),1,f);
printf("%d\n",r.x);
sleep(4);
}
fclose(f);
printf("\n");
sleep(4);
/* use fseek to read the 10 records in reverse order */
f=fopen("junk","r");
for (i=9; i>=0; i--)
{
fseek(f,sizeof(struct rec)*i,SEEK_SET);
fread(&r,sizeof(struct rec),1,f);
printf("%d\n",r.x);
sleep(4);
}
fclose(f);
printf("\n");
sleep(4);
/* use fseek to read every other record */
f=fopen("junk","r");
fseek(f,0,SEEK_SET);
for (i=0;i<5; i++)
{
fread(&r,sizeof(struct rec),1,f);
printf("%d\n",r.x);
sleep(4);
fseek(f,sizeof(struct rec),SEEK_CUR);
}
fclose(f);
printf("\n");
sleep(4);
/* use fseek to read 4th record, change it, and write it back */
f=fopen("junk","r+");
fseek(f,sizeof(struct rec)*3,SEEK_SET);
fread(&r,sizeof(struct rec),1,f);
r.x=100;
fseek(f,sizeof(struct rec)*3,SEEK_SET);
fwrite(&r,sizeof(struct rec),1,f);
fclose(f);
printf("\n");
sleep(4);
/* read the 10 records to insure 4th record was changed */
f=fopen("junk","r");
for (i=1;i<=10; i++)
{
fread(&r,sizeof(struct rec),1,f);
printf("%d\n",r.x);
sleep(4);
}
fclose(f);
}
It only minipulates the x value in the struct writes reads and changes a value in that certain position. I need my struct to do the same thing but have know idea how to start.
I know I put alot in this post but i've been looking into this for a while and cant seem to get anyware.