ConectarDB.php

<?php

function conectar($nameDB = '', $userDB = '', $passDB = '') {

  if ($nameDB !== ''|| $userDB !== ''|| $passDB !== '') {

    try {

      $link = new PDO (
        'mysql:host=localhost;
        dbname=' . $nameDB . '',
        $userDB,
        $passDB
      );
            
      } catch (PDOException $e) {
        
        print '¡Error!: ' . $e->getMessage() . '<br/>';

        die();

      }

  } else {

    echo '¡Error al conectar!';

  }

  return $link;

}