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Validating e-mail, URL and other special types with PHP

On this page we will show a few examples of how to validate e-mails, website addresses (URLs) and some other special cases of input data.

» Validate e-mail address

There is no way to be 100% sure an e-mail address is actually working unless you send an e-mail there. What you usually do is check if the e-mail address syntax is valid. Here is a simple way to check if data entered into input field named "email" is an e-mail address without any unnecessary complications and fancy regular expressions:

$email = htmlspecialchars($_POST['email']);
if (!preg_match("/([\w\-]+\@[\w\-]+\.[\w\-]+)/",$email))
{
    die("E-mail address not valid");
}

The above code would make the e-mail address required. To make it optional simply replace

    die("E-mail address not valid");

with this and the $email variable will simply be empty unless a valid address is entered:

    $email = '';

» Validate URL address

If you have an input field named "website" you can check for a valid URL address like this:

$url = htmlspecialchars($_POST['website']);
if (!preg_match("/^(https?:\/\/+[\w\-]+\.[\w\-]+)/i",$url))
{
    die("URL address not valid");
}

Similarly as before to make the URL optional just change:

    die("URL address not valid");

to this code and $url will be empty if not valid:

    $url = '';

» Other special cases

Some other special cases below if you ever need any. You may just skip it and go to the next page of the tutorial.

Digits 0-9 only

This code will check if $age is a number:

if (preg_match("/\D/",$age))
{
    die("Please enter numbers only for Age");
}

Letters a-z and A-Z only

This code will check if $text is made of letters a-z and A-Z only (no spaces, digits or any other characters):

if (preg_match("/[^a-zA-Z]/",$text))
{
    die("Please enter letters a-z and A-Z only!");
}

Anything but whitespace

This code will show an error if $text contains of any whitespace characters (space, tab, newline):

if (preg_match("/\s/",$text))
{
    die("Please do not enter any spaces, tabs or new lines!");
}

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