PHP Read txt file and check if username password exists - php

Question

I have a bunch of passwords and usernames stored in a txt file and i need to check for matches. I know this is not a safe method but its for leaning purposes.
This code writes the usernames and passwords to a txt file
if(isset($_POST['register'])) //
{
$user = $_POST['username'];
$password=$_POST['password'].PHP_EOL;
$fh = fopen("file.txt","a+");
fwrite($fh,$user." ".$password); //write to txtfile
fclose($fh);
}
Here's the code im having trouble with.
Username and Passwords are stored like this in results
username1 passwords1 username2 password2 etc.
So I need to check if result[0] = userinput AND if it exists check if result[1] = passwordInput and so on.
if(isset($_POST['Logg']))
{
//$_SESSION['username']=$user;
//$_SESSION['password']=$password;
$file = file_get_contents("file.txt"); // Returns a string
$result = explode(" ",$file);
$boolC= false;
for($i=0; $i< count($result); $i++)
{
if($result[$i] === $user)
{
$boolC=true;
$i =$i+1;
if($boolC === true)
{
if($result[$i]===$password)
{
echo 'Password and Username Correct';
}
}
}
}
}

Answer 1

Consider the possibility of having a space in the password so as any symbols. Perhaps you should split on a line break ("\n").
if( $result[$i] === $user && $result[$i+1] === $password )
The first part of the statement has to be true for the second one to be evaluated.
The $i variable is never changed
$file = "username1 passwords1 username2 password2";
$result = explode(" ",$file);
$user = "username1";
$password = "passwords1";
for($i=0; $i< count($result); $i++){
if($result[$i] === $user && $result[$i+1] === $password)
{
echo 'Password and Username Correct';
}
}

Answer 2

Before you go ahead and try to correct this code, I strongly suggest you stay away from storing passwords in a plain text file. It is a huge security hole in your system.
Another architecture issue I can see is that your code would fail if the username or passwords contain a space in them. You probably should use line jumps as a delimiter instead (\n).

Answer 3

I think there is nothing wrong with the logic of the original post.
You should print all the variables to check whether they hold the correct value or not.
the "$user" and "$password" variables are global or not since they would not be known within the braces of the other if block i.e in the block where you check $_POST['logg']