I need to write PHP code to edit my pages so the link in the home page that says "Not available unless you are Admin", can only be accessed by admin. The admin credentials are username ("admin") and password ("dcsadmin01"). Also please note that all credentials are saved in a text file (users.txt). Please have a look on the pages below:

login.php

// session start

session_start();

if(isset($_POST['login'])) // it checks whether the user clicked login button or not

{

$user = $_POST['username'];

$pass = $_POST['password'];

if(isset($_POST["username"]) && isset($_POST["password"])){

$file = fopen('users.txt', 'r');

$good=false;

while(!feof($file)){

$line = fgets($file);

$array = explode(";",$line);

if(trim($array[0]) == $_POST['username'] && trim($array[1]) == $_POST['password']){

$good=true;

break;

}

} if($good){

$_SESSION['username'] = $user;

echo "";

}else{

echo "Invalid UserName or Password";

}

fclose($file);

}

}

?>

Login Page
Username
Password
If you want to go back to index page click here

home.php

// session starts with the help of this function

session_start();

$userid='';

//check session is set or not

if(isset($_SESSION["username"])){

//get the username and store in variable

$userid=$_SESSION["username"];

}

else{

header("Location:login.php");

}

?>

Welcome:

Logout

DTresults,

P1results, PfPresults Not available unless you are Admin

admin.php

session_start();

$userid='';

//check session is set or not

if(isset($_SESSION["username"])){

//get the username and store in variable

$userid=$_SESSION["username"];

}

else{

header("Location:login.php");

}

// if submit form we get data from $_POST method

if(isset($_POST["username"]) && isset($_POST["password"]))

{

// check if user file exist.

$file=fopen("users.txt","r");

$finduser = false;

while(!feof($file))

{

//get the data in line

$line = fgets($file);

// split username and password and store in array which is save in users.txt file

$array = explode(";",$line);

if(trim($array[0]) == $_POST['username'])

{

$finduser=true;

break;

}

}

fclose($file);

// register user or pop up message

if( $finduser )

{

echo $_POST["username"];

echo ' existed! ';

include 'admin.php';

}

else

{

// save data in text file

$file = fopen("users.txt", "a");

fputs($file,$_POST["username"].";".$_POST["password"]." ");

fclose($file);

// print register username

echo $_POST["username"];

echo " registered successfully!";

}

}

?>

Register new user
Username
Password
	If you want to go to home page click here Or if you want to log out click logout