<head>
<style>
.error {color: #FF0000;}
</style>
</head>
 

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

if ($_SERVER["REQUEST_METHOD"] == "POST")
{
&nbsp;&nbsp; if (empty($_POST["name"]))
&nbsp;&nbsp;&nbsp;&nbsp; {$nameErr = "Name is required";}
&nbsp;&nbsp; else
&nbsp;&nbsp;&nbsp;&nbsp; {
&nbsp;&nbsp;&nbsp;&nbsp; $name = test_input($_POST["name"]);
&nbsp;&nbsp;&nbsp;&nbsp; // check if name only contains letters and whitespace
&nbsp;&nbsp;&nbsp;&nbsp; if (!preg_match("/^[a-zA-Z ]*$/",$name))
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; {
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; $nameErr = "Only letters and white space allowed"; 
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; }
&nbsp;&nbsp;&nbsp;&nbsp; }
&nbsp;&nbsp; 
&nbsp;&nbsp; if (empty($_POST["email"]))
&nbsp;&nbsp;&nbsp;&nbsp; {$emailErr = "Email is required";}
&nbsp;&nbsp; else
&nbsp;&nbsp;&nbsp;&nbsp; {
&nbsp;&nbsp;&nbsp;&nbsp; $email = test_input($_POST["email"]);
&nbsp;&nbsp;&nbsp;&nbsp; // check if e-mail address syntax is valid
&nbsp;&nbsp;&nbsp;&nbsp; if (!preg_match("/([w-]+@[w-]+.[w-]+)/",$email))
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; {
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; $emailErr = "Invalid email format"; 
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; }
&nbsp;&nbsp;&nbsp;&nbsp; }
&nbsp;&nbsp;&nbsp;&nbsp; 
&nbsp;&nbsp; if (empty($_POST["website"]))
&nbsp;&nbsp;&nbsp;&nbsp; {$website = "";}
&nbsp;&nbsp; else
&nbsp;&nbsp;&nbsp;&nbsp; {
&nbsp;&nbsp;&nbsp;&nbsp; $website = test_input($_POST["website"]);
&nbsp;&nbsp;&nbsp;&nbsp; // check if URL address syntax is valid (this regular expression also allows dashes in the URL)
&nbsp;&nbsp;&nbsp;&nbsp; if (!preg_match("/(?:(?:https?|ftp)://|www.)[-a-z0-9+&@#/%?=~_|!:,.;]*[-a-z0-9+&@#/%=~_|]/i",$website))
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; {
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; $websiteErr = "Invalid URL"; 
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; }
&nbsp;&nbsp;&nbsp;&nbsp; }

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

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

function test_input($data)
{
&nbsp;&nbsp;&nbsp;&nbsp; $data = trim($data);
&nbsp;&nbsp;&nbsp;&nbsp; $data = stripslashes($data);
&nbsp;&nbsp;&nbsp;&nbsp; $data = htmlspecialchars($data);
&nbsp;&nbsp;&nbsp;&nbsp; return $data;
}
?>

<h2>PHP Form Validation Example</h2>
<p><span class="error">* required field.</span></p>
<form method="post" action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]);?>"> 
&nbsp;&nbsp; Name: <input type="text" name="name" value="<?php echo $name;?>">
&nbsp;&nbsp; <span class="error">* <?php echo $nameErr;?></span>
&nbsp;&nbsp; 


&nbsp;&nbsp; E-mail: <input type="text" name="email" value="<?php echo $email;?>">
&nbsp;&nbsp; <span class="error">* <?php echo $emailErr;?></span>
&nbsp;&nbsp; 


&nbsp;&nbsp; Website: <input type="text" name="website" value="<?php echo $website;?>">
&nbsp;&nbsp; <span class="error"><?php echo $websiteErr;?></span>
&nbsp;&nbsp; 


&nbsp;&nbsp; Comment: <textarea name="comment" rows="5" cols="40"><?php echo $comment;?></textarea>
&nbsp;&nbsp; 


&nbsp;&nbsp; Gender:
&nbsp;&nbsp; <input type="radio" name="gender" <?php if (isset($gender) && $gender=="female") echo "checked";?>&nbsp; value="female">Female
&nbsp;&nbsp; <input type="radio" name="gender" <?php if (isset($gender) && $gender=="male") echo "checked";?>&nbsp; value="male">Male
&nbsp;&nbsp; <span class="error">* <?php echo $genderErr;?></span>
&nbsp;&nbsp; 


&nbsp;&nbsp; <input type="submit" name="submit" value="Submit"> 
</form>

<?php
echo "<h2>Your Input:</h2>";
echo $name;
echo "<br />";
echo $email;
echo "<br />";
echo $website;
echo "<br />";
echo $comment;
echo "<br />";
echo $gender;
?>