PHP - Comparing Array Keys and Values

Question

I'm attempting a simple array scenario, partially for practice with arrays. The code below is simply comparing a username and password variable combo to merged arrays.

It works, but I think it can be improved drastically.

<?php 
$username = 'demo@demo.com';    
$password = '123456';   

$allowed_creds1 = array('demo@demo.com'=>'123456');
$allowed_creds2 = array('john@smith.com'=>'654321');
$allowed_creds3 = array('jane@doe.com'=>'124578');
$mergedArrays = array_merge($allowed_creds1, $allowed_creds2, $allowed_creds3);

foreach($mergedArrays as $key => $val){
    echo "$key, $val \n";
    if($username == $key && $password == $val){ 
        die("Valid Username and Password");
    }
}
?>

Ideally I'd like to validate with a true/false return so I can do more. I've considered placing the foreach loop inside a custom function that returns a boolean value, but before I start complicating it, I feel I should ask if there's a better way to validate my php variables to the merged arrays.

Answer 1

There is no need to iterate over an array when you know the key you are looking for. Simply check for the value using the key.

if ( $mergedArrays[$username] == $password ) {
    return TRUE;
}

Answer 2

Since you're using the username as the array key, you can simply check for the existence of the key:

if (!empty($mergedArrays[$username]) && $mergedArrays[$username] === $password) {
    return true;
}

Note that this makes the username case sensitive (many users may not expect this). Note the strict comparison (===). When comparing strings in this way, you'll need to avoid numeric casting which can lead to incorrect results. For instance:

echo ('0x04d' == '77'); // returns true

Of course, normally you should be storing and checking this information via hashes/encryption in the database.

Answer 3

Check if there is a key called your $username and then check if the element with this key has a valid value equal to password:

if (array_key_exists($username , $mergedArrays)) {
   if(password==$mergedArrays[$username]) return true;
}