PHP, Undefined offset: 1 - php

Question

I wanted to build a super-simple login-script with a text-file. Text-file contains
password username name
Between the password, username and name is a tab. I read the file, explode it by tab, and then check the user input against the lines.
But I always get (one) Undefined offset error. I think it is because of the explode function, but I don't know why...
Here's my code:
if(!empty($_POST['login_inputEmail']) || !empty($_POST['login_inputPassword']))
{
$log = 0; //not logged in
$username = $_POST['login_inputEmail'];
$password = $_POST['login_inputPassword'];
$userdatei = fopen ("documents/user.txt","r");
while (!feof($userdatei))
{
$zeile = fgets($userdatei,800);
$userdata = explode("\t", $zeile);
if ($username == $userdata[1] && $password == trim($userdata[0]))
{
$log = 1; //logged in
}
}
fclose($userdatei);
}

Answer 1

Add is_array() and isset() in your code to avoid errors. Refer this
if(!empty($_POST['login_inputEmail']) || !empty($_POST['login_inputPassword']))
{
$log = 0; //not logged in
$username = $_POST['login_inputEmail'];
$password = $_POST['login_inputPassword'];
$userdatei = fopen ("documents/user.txt","r");
while (!feof($userdatei))
{
$zeile = fgets($userdatei,800);
$userdata = explode("\t", $zeile);
if(is_array($userdata))
{
if(isset($userdata[1]) && isset($userdata[0]))
{
if ($username == $userdata[1] && $password == trim($userdata[0]))
{
$log = 1; //logged in
}
}
}
}
fclose($userdatei);
}