php regular expression pass variable code example

Example 1: 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";
}
?>

Example 2: php preg match space or start of string

/\b(stackoverflow)\b/