There is a small error in the code | I’ll fix it soon. If you know it, let me know as well
<?php //php protion ?>
<?php
// Firstly I have defined the variables here and set them to empty values
$websiteErr = "";
if(isset($_post["btn"])){
$web = $_post["site"];
if (!preg_match("/b(?:(?:https?|ftp)://|www.)[-a-z0-9+&@#/%?=~_|!:,.;]*[-a-z0-9+&@#/%=~_|]/i",$web)) {
$websiteErr = "Invalid URL";
}
}
?>
<?php //html portion ?>
<!DOCTYPE HTML>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Simple html form by TALHA SHOAIB</title>
</head>
<body>
<h3>Web Url validation | code avaialble at <a href="https://techkwave.blogspot.com/">Tech wave</a></h3>
<form action="" method="post">
<label>Website Url:</label>
<input type="text" name="site">
<span style="color: red;">*<?php echo $websiteErr; ?></span>
<br>
<input type="submit" name="btn" value="Button">
</form>
</body>
</html>