PHP - if conditional statement skipped unless an else is specified - php

Question

I created a very simple login page where I validate the username and password on PHP after submitting the form.
My first step in the validation is to check that the username and password are not empty, if empty I send the user back to the login page:
$e = $_POST['email'];
$p = $_POST['password'];
if($e == '' || $p == '' || is_null($e) || is_null($p)){
header('Location: login.php?e=missing');
}
it turns out that the if statement that checks if the username and password are empty only works if I add an else statement:
$e = $_POST['email'];
$p = $_POST['password'];
if($e == '' || $p == '' || is_null($e) || is_null($p)){
header('Location: login.php?e=missing');
}else{
//more validation
}
To be honest, my code works, I added the else and problem solved, but WHY???
Thanks.

Answer 1

$e = $_POST['email'];
$p = $_POST['password'];
if(trim($e) == '' || trim($p) == ''){
header('Location: login.php?e=missing');
exit(); // add this else it wont leave the page!
}else{
//more validation
}

Answer 2

if($e == '' || $p == ''){
header('Location: login.php?e=missing');
}
You need to add an exit() after the header line; otherwise, processing continues as normal and all the rest of the code is run.

Answer 3

you need to use empty to check if the variables are set, as well as empty.
$e = $_POST['email'];
$p = $_POST['password'];
if( empty($e) || empty($p) ) {
header('Location: login.php?e=missing');
exit;
}
else {
//more validation
}

Answer 4

$e = $_POST['email'];
$p = $_POST['password'];
if(!empty($e) && !empty($p))
{
header('Location: login.php?e=missing');
exit();
}
else
{
//more validation
}

Answer 5

if($e == '' || $p == ''){
header('Location: login.php?e=missing');
}
rathen then that use :
if(!isset($e) || !isset($p)){
header('Location: login.php?e=missing');
exit();
}
It is happens because of white space or you can use trim() function to remove white space and use exit(); after header its mandatory*