preg_match — Perform a regular expression match for email,name ,URL

see code below for example.php:

Read explanation of above used preg_match():

PHP - Validate E-mail

The easiest and safest way to check whether an email address is well-formed is to use PHP's filter_var() function.

In the code below, if the e-mail address is not well-formed, then store an error message:

$email = test_input($_POST["email"]);if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {  $emailErr = "Invalid email format"; }

PHP - Validate URL

The code below shows a way to check if a URL address syntax is valid (this regular expression also allows dashes in the URL). If the URL address syntax is not valid, then store an error message:

$website = test_input($_POST["website"]);if (!preg_match("/\b(?:(?:https?|ftp):\/\/|www\.)[-a-z0-9+&@#\/%?=~_|!:,.;]*[-a-z0-9+&@#\/%=~_|]/i",$website)) {  $websiteErr = "Invalid URL"; }

PHP - Validate Name

The code below shows a simple way to check if the name field only contains letters and whitespace. If the value of the name field is not valid, then store an error message:

$name = test_input($_POST["name"]);if (!preg_match("/^[a-zA-Z ]*$/",$name)) {  $nameErr = "Only letters and white space allowed"; }

//function code:

function test_input($data) {   $data = trim($data);   $data = stripslashes($data);   $data = htmlspecialchars($data);   return $data;}