User Login and Registration using Files in C

Vishal Sharma · Jun 17, 2012

Rank B3 - LEADER

Hello Everyone!! i'm working on this C program which deals with user registration and login page. I was successful is writing the program for only 1 user. But now when i'm trying it for 100 users, i get a few problems that are:

1. The program starts with registering 1st user records in w[0], it works fine if i login at this time.. But, when I close the program and restart it to make the second registration, again it starts with w[0] which copies the same username and password as the 1st registration.. How to overcome this problem???

2. if I take just w instead of w[99] and make the necessary adjustments in the program, I'm able to get 2 different username's and passwords in the file but at the time of login, if program is able to read any of the username and password, it logs in..
ex: suppose there are two username's and passwords (username followed by the password) as,
abc pass abc1 pass1

now, at the time of log in, if user enters username as abc and password as pass1, the program must not log in.. but it does.

NEED SUGGESTIONS!!

below, is the C code i've written.
I'm facing problem in void reg() and void login()

#include<conio.h>
#include<stdio.h>
#include<string.h>
static int i=0;
struct web
{
char name[30],pass[30];
}w[99];
int n;
void login(void);
void reg(void);
int main()
{
clrscr();
printf("\n\n\n\n\n\t\t\t\tWELCOME TO MY WEBSITE");
printf("\n\t\t\t\t=====================");
printf("\n\n\n\n\t\t\tPress Enter to proceed...!!");
if(getch()==13)
  clrscr();
XY:
printf("\n\n\n\t\t\t1. LOGIN\t\t2. REGISTER");
printf("\n\n\n\t\t\t\tENTER YOUR CHOICE: ");
scanf("%d",&n);
switch(n)
  {
    case 1: clrscr();
        login();
        break;
    case 2: clrscr();
        reg();
        break;
    default: printf("\n\n\t\t\t\tNO MATCH FOUND");
        printf("\n\n\t\t\tPress Enter to re-Enter the choice");
        if(getch()==13)
        clrscr();
        goto XY;
  }
  return 0;
}
void reg()
  {
    FILE *fp;
    char c,checker[30]; int z=0;
    fp=fopen("Web_reg.txt","ab+");
    printf("\n\n\t\t\t\tWELCOME TO REGISTER ZONE");
    printf("\n\t\t\t\t^^^^^^^^^^^^^^^^^^^^^^^^");
    for(i=0;i<100;i++)
    {
      printf("\n\n\t\t\t\t  ENTER USERNAME: ");
      scanf("%s",checker);
        while(!feof(fp))
        {
          fread(&w[i],sizeof(w[i]),1,fp);
          if(strcmp(checker,w[i].name)==0)
            {
            printf("\n\n\t\t\tUSERNAME ALREDY EXISTS");
            clrscr();
            reg();
            }
          else
          {
            strcpy(w[i].name,checker);
            break;
          }
        }
      printf("\n\n\t\t\t\t  DESIRED PASSWORD: ");
      while((c=getch())!=13)
        {
          w[i].pass[z++]=c;
          printf("%c",'*');
        }
      fwrite(&w[i],sizeof(w[i]),1,fp);
      fclose(fp);
      printf("\n\n\tPress enter if you agree with Username and Password");
      if((c=getch())==13)
        {
        clrscr();
        printf("\n\n\t\tYou are successfully registered");
        printf("\n\n\t\tTry login your account??\n\n\t\t  ");
        printf("> PRESS 1 FOR YES\n\n\t\t  > PRESS 2 FOR NO\n\n\t\t\t\t");
        scanf("%d",&n);
        switch(n)
          {
              case 1: clrscr();
                    login();
                    break;
              case 2: clrscr();
                    printf("\n\n\n\t\t\t\t\tTHANK YOU FOR REGISTERING");
                    break;
          }
        }
        break;
      }
    getch();
  }
  void login()
    {
      FILE *fp;
      char c,name[30],pass[30]; int z=0;
      int checku,checkp;
      fp=fopen("Web_reg.txt","rb");
      printf("\n\n\t\t\t\tWELCOME TO LOG IN ZONE");
      printf("\n\t\t\t\t^^^^^^^^^^^^^^^^^^^^^^");
      for(i=0;i<1000;i++)
      {
        printf("\n\n\t\t\t\t  ENTER USERNAME: ");
        scanf("%s",name);
        printf("\n\n\t\t\t\t  ENTER PASSWORD: ");
        while((c=getch())!=13)
        {
          pass[z++]=c;
          printf("%c",'*');
        }
        pass[z]='\0';
      while(!feof(fp))
        {
        fread(&w[i],sizeof(w[i]),1,fp);
          checku=strcmp(name,w[i].name);
          checkp=strcmp(pass,w[i].pass);
          if(checku==0&&checkp==0)
          {
            clrscr();
            printf("\n\n\n\t\t\tYOU HAVE LOGGED IN SUCCESSFULLY!!");
            printf("\n\n\n\t\t\t\tWELCOME, HAVE A NICE DAY");
            break;
          }
        else if(checku==0&&checkp!=0)
          {
            printf("\n\n\n\t\t\tWRONG PASSWORD!! Not %s??",name);
            printf("\n\n\t\t\t\t  (Press 'Y' to re-login)");
            if(getch()=='y'||getch()=='Y')
              login();
          }
        else if(checku!=0)
          {
            printf("\n\n\n\t\t\tYou are not a Registered User\n \t\t\tPress enter to register yourself");
            if(getch()==13)
            clrscr();
            reg();
          }
        }
        break;
      }
      getch();
    }

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User Login and Registration using Files in C

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