PHP Forms - Validate E-mail and URL

This chapter show how to validate names, e-mails, and URLs.

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";
  }

PHP - Validate E-mail

The code below shows a simple way to check if an e-mail address syntax is valid. If the e-mail address syntax is not valid, then store an error message:

$email = test_input($_POST["email"]);
if (!preg_match("/([\w\-]+\@[\w\-]+\.[\w\-]+)/",$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";
  }

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PHP - Validate Name, E-mail, and URL

Now, the script looks like this:

Example

<?php
// define variables and set to empty values
$nameErr = $emailErr = $genderErr = $websiteErr = "";
$name = $email = $gender = $comment = $website = "";

if ($_SERVER["REQUEST_METHOD"] == "POST")
{
  if (empty($_POST["name"]))
    {$nameErr = "Name is required";}
  else
    {
    $name = test_input($_POST["name"]);
    // check if name only contains letters and whitespace
    if (!preg_match("/^[a-zA-Z ]*$/",$name))
      {
      $nameErr = "Only letters and white space allowed";
      }
    }

  if (empty($_POST["email"]))
    {$emailErr = "Email is required";}
  else
    {
    $email = test_input($_POST["email"]);
    // check if e-mail address syntax is valid
    if (!preg_match("/([\w\-]+\@[\w\-]+\.[\w\-]+)/",$email))
      {
      $emailErr = "Invalid email format";
      }
    }

  if (empty($_POST["website"]))
    {$website = "";}
  else
    {
    $website = test_input($_POST["website"]);
    // check if URL address syntax is valid (this regular expression also allows dashes in the URL)
    if (!preg_match("/\b(?:(?:https?|ftp):\/\/|www\.)[-a-z0-9+&@#\/%?=~_|!:,.;]*[-a-z0-9+&@#\/%=~_|]/i",$website))
      {
      $websiteErr = "Invalid URL";
      }
    }

  if (empty($_POST["comment"]))
    {$comment = "";}
  else
    {$comment = test_input($_POST["comment"]);}

  if (empty($_POST["gender"]))
    {$genderErr = "Gender is required";}
  else
    {$gender = test_input($_POST["gender"]);}
}
?>