how to use regex expression in php code example

Example 1: regex php

<?php
// First Verif your regex code with https://regex101.com/
$str = "Visit W3Schools";
$pattern = "/w3schools/i";
echo preg_match($pattern, $str); // Outputs 1

// test email with REGEX
if (!preg_match("/[-0-9a-zA-Z.+_]+@[-0-9a-zA-Z.+_]+.[a-zA-Z]{2,4}/", $emailAddress)){
    //Email address is invalid.
}

// use filter var to valide Email
if(filter_var($emailAddress, FILTER_VALIDATE_EMAIL)) 
{
     //The email address is valid.
} else{
     //The email address is invalid.
}


?>

Example 2: preg_match in php

<?php
$my_email = "[email protected]";
if (preg_match("/^[a-zA-Z0-9._-]+@[a-zA-Z0-9-]+\.[a-zA-Z.]{2,5}$/", $my_email)) {
echo "$my_email is a valid email address";
}
else
{
  echo "$my_email is NOT a valid email address";
}
?>