User Login and Registration using Files in C

Uday Bidkar

I don't have a C compiler with me, but do see some potential errors in code.

0) The way you check for "user name exist" is faulty. You are not going through entire file to search the username. The first failure to match the user name breaks the loop.
1) I can see you are using recursion in case user name already exists. Close the file pointer before the call to reg() and call "return" just after you call reg(). This will ensure that the calling reg() wont continue below that point when the called reg() returns.
Recursion is extremely great tool and at the same time very dangerous if not used right 😀
2) You don't initialize the value of z to zero before setting the password for a new user

Try fixing these first and we'll take take it from there later.

Vishal0203

This is a very old thread!
Problem has been rectified long back!

Joshua Dani M

@Vishal0203 please send the complete code!

Vishal0203

Hey, I'm afraid i do not have this code with me anymore, as you see this is a 4-5 year old thread. However, you can use struct to solve this.

Open the file in binary mode, write the struct with username and password to the file. You can then load the data of the file as initialization and store it in array of structs. Then take the input of username and password and check your array for the match.

Note : this solution is not optimal, but my requirements weren't that great.

Joshua Dani M

Thank you! But i'm not that great in programming! could you modify the above program...it will be very helpful to me...and ill be grateful to you

Vishal0203

No assignment helps.

Joshua Dani M

Thank you! But i'm not that great in programming! could you modify the above program...it will be very helpful to me...and ill be grateful to you

Joshua Dani M

But isnt that what you did in the code @Vishal0203 ? Or am i mistaken?

#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();

    }

Posting on behalf of @tulluru 

Registration process:

the system should check the admin is a existing user,if he is not then the system should check the admin is a student or a faculty.If he is a student then the system should take all the required details for the registration process and make a username and password for the new user to login the college website in future.the same is required for the faculty too.

I have tried to execute the code but there is a problem.Once a person has registered and tries to login the system still says "you aren't a registered user" could you help in this regard.Please reply at the earliest!

I have tried to execute the code but there is a problem.twice a person has registered and tries to login the system it says "you aren't a registered user" could you help in this regard.Please reply at the earliest! Tomorrow i have to submit my project to my teacher

Rakibul Pranto,How did you solve this problem? I'd really appreciate if you reply ASAP.

1. #include <stdio.h>
2. #include <string.h>
3. #include <conio.h>
4.  
5. int main()
6. {
7.     char username[15];
8.     char password[12];
9.  
10.  
11.     printf("Enter your username:\n");
12.     scanf("%s",&username);
13.  
14.     printf("Enter your password:\n");
15.     scanf("%s",&password);
16.  
17.     if(strcmp(username,"chai")==0){
18.         if(strcmp(password,"123")==0){
19.  
20.         printf("\nWelcome.Login Success!");
21.  
22.  
23.         }else{
24.     printf("\nwrong password");
25. }
26.     }else{
27.     printf("\nUser doesn't exist");
28. }
29.     return 0;
30. }
31. 
    

/* login.c
Author: Jake Rodriguez Pomperada,MAED-IT
Website: http://www.jakerpomperada.com
Emails: jakerpomperada@gmail.com and jakerpomperada@aol.com
Location : Bacolod City, Negros Occidental
Tool : Dev C++ Version 5.11
Date : January 7, 20193:46 PM Monday
*/
#include <stdio.h>
#include <conio.h>
#include <stdlib.h>
#include <string.h>
void get_ID_and_PASS(char fileName[30],char *id,char *pass)
{
FILE *F = fopen(fileName,"r");
if(F)
{
int count = 0;
while(!feof(F))
{
char rawLine[50];
fscanf(F,"%s",rawLine);
if(!count++)
strcpy(id,rawLine);
else
strcpy(pass,rawLine);
}
}else printf("Cannot open this file");
fclose(F);
}
int main()
{
char fileName[30] = "users.txt";
char userID[50],userPassW[50];
char strID[50]="\0",strPASSW[50]="\0";
char IDpref[50] = "user_id:\0",PASSWpref[50] = "password:\0";
get_ID_and_PASS(fileName,userID,userPassW);
char c;
int pos = 0;
printf("\n\n");
printf("\tLOGIN SECURITY SYSTEM IN C USING TEXT FILES");
printf("\n\n");
printf("\tEnter User Name : ");
scanf("%s",&strID);
printf("\n");
printf("\tEnter Your Password : ");
do {
c = getch();
if( isprint(c) )
{
strPASSW[ pos++ ] = c;
printf("%c", '*');
}
else if( c == 9 && pos )
{
strPASSW[pos--] = '\0';
printf("%s", "\b \b");
}
} while( c != 13 );
strcpy(strID,strcat(IDpref,strID));
strcpy(strPASSW,strcat(PASSWpref,strPASSW));
if (!strcmp(strID,userID)&&!strcmp(strPASSW,userPassW))
{
printf("\n\n");
printf("\tCorrect Username And Password\n");
printf("\n\n\tWelcome to the System\n\n");
}
else
{
printf("\n\n");
printf("\tInvalid Username And Password. Try Again\n\n");
}
printf("\n\n");
printf("\tEND OF PROGRAM");
printf("\n\n");
system("pause");
}