#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <conio.h>

struct database
{
  char user[20];
  char pass[20];
  char email[40];
}record;

int main()
{
    int count, choice, entries, i, j, ls, check=0;
    char mask;
    char fileDump[10000][50];
    char username[20];
    char password[20];
    FILE *fptr = fopen("E:\login_practice.bin","ab+");
    char dump[256];
    Again:
    printf("Welcome to user authentication program v1.2n");
    printf("n1. Registern");
    printf("n2. Loginn");
    printf("n3. Exitn");
    printf("nEnter your choice: ");
    scanf("%d", &choice);
    switch(choice)
    {
        case 1:
            printf("nHow many user you want to register?n");
            printf("nUsers = ");
            scanf("%d", &entries);
            for(count=1; count<=entries; count++)
            {
                FILE *fp = fopen("E:\email.bin", "ab+");
                printf("nEnter your email: ");
                scanf("%s", &record.email);
                fprintf(fp, "%sn", record.email);
                fclose(fp);

                printf("nEnter a username: ");
                scanf("%s", &record.user);
                fprintf(fptr, "%sn", record.user);

                printf("nEnter a password: ");
                for(j=0; j<10; j++)
                {
                    mask = getch();
                    if(mask == 13)
                    {
                        break;
                    }
                    else
                    {
                        record.pass[j] = mask;
                        mask = '*';
                        printf("%c", mask);
                    }
                }
                fprintf(fptr, "%sn", record.pass);
                printf("nRegistration Successful.n");
            }
            goto Again;
            break;

    case 2:
        i=0;
        while(fgets(dump, sizeof(dump),fptr))
        {
            strcpy(fileDump[i], dump);
            i++;
        }
        ls=i;
        printf("nLines Scanned = %dn", ls);
        printf("nEnter your username: ");
        scanf("%s", &username);
        printf("nEnter your password: ");
        for(j=0; j<10; j++)
        {
            mask = getch();
            if(mask == 13)
            {
                break;
            }
            else
            {
                password[j] = mask;
                mask = '*';
                printf("%c", mask);
            }
        }
        strcat(username, "n");
        strcat(password, "n");
        for(i=0; i<=ls; i+=2)
        {
            if(strcmp(fileDump[i], username)==0)
            {
                if(strcmp(fileDump[i+1], password)==0)
                {
                    check++;
                }
            }

        }
        if(check == 1)
        {
            printf("nLogin Successful.n");
        }
        else
        {
            printf("nInvalid Details Entered!n");
        }
        goto Again;
        break;

    case 3:
        exit(0);
        break;

    default:
        printf("nBad Choice!n");
        goto Again;
        break;
    }
fclose(fptr);
}