Compare strings and only get certain strings that don't match

Question

I have a few strings and i want the variables that don't equal each other.

For example:

$username
$email
$firstname
$lastname
$gender

$_POST['username'];
$_POST['email'];
$_POST['firstname'];
$_POST['lastname'];
$_POST['gender'];

i want to compare $username with $_POST['username'] , $email with $_POST['email'] , etc...

this is how i want to compare it:

$username !== $_POST['username'] , etc...

how can i get the variables (not $_POST variables) that DON'T equal each other?

Answer 1

with so many values, and if you know the fields that are coming at you, I would use arrays.

$vars = ['username' => 'value', 'email' => 'value',
        'firstname' => 'value', 'lastname' =>'value', 'gender'  => 'value'];
foreach($vars as $key => $value){
  if($_POST[$key] !== $value){
    //does not match
  }else{
    // does match
  }
}

Answer 2

Since the POST parameters are coming in as an array, the simplest approach would be to put your variables also in an array and calculate the difference using array_diff :

$variables = [
    'username' => $username,
    'email' => $email,
    'firstname' => $firstname,
    'lastname' => $lastname,
    'gender' => $gender
];

$non_matching = array_diff($variables, $_POST);

echo "Non matching variables: " . join(', ', array_keys($non_matching));

Which will print out something like:

Non matching variables: username, firstname

Answer 3

You can use foreach to each array key and $$key to do.

$username = 'username';
$email    = 'email~';
$gender   = 'not gender';

$_POST['username']  = 'username';
$_POST['email']     = 'email';
$_POST['firstname'] = 'firstname';
$_POST['lastname']  = 'lastname';
$_POST['gender']    = 'gender';

foreach ($_POST as $key => $value) {
    if ( !isset($$key) ) {
        echo 'The variable $' . $key . ' is undefined.' . PHP_EOL;
        continue;
    }
    echo 'Compare $_POST[\'' . $key . '\'] and $' . $key . ': ' . ( $value === $$key ? 'true' : 'false' ) . PHP_EOL;
}

Result:

Compare $_POST['username'] and $username: true
Compare $_POST['email'] and $email: false
The variable $firstname is undefined.
The variable $lastname is undefined.
Compare $_POST['gender'] and $gender: false