Form validation is necessary in many cases if user filling signup form than some fields are must be required on server side to handle this type of situations we use form validation.
<!DOCTYPE HTML>
<html>
<head>
<style>
.error {color: #FF0000;}
</style>
</head>
<body>
<?php
// define variables and set to empty values
$usernameErr = $emailErr = $infoErr = "";
$username = $email = $info = "";
if ($_SERVER["REQUEST_METHOD"] == "POST") {
if (empty($_POST["username"])) {
$usernameErr = "Name is required";
} else {
$username = test_input($_POST["username"]);
}
if (empty($_POST["email"])) {
$emailErr = "Email is required";
} else {
$email = test_input($_POST["email"]);
}
if (empty($_POST["info"])) {
$infoErr = "";
} else {
$info = test_input($_POST["info"]);
}
}
function test_input($data) {
$data = trim($data);
$data = stripslashes($data);
$data = htmlspecialchars($data);
return $data;
}
?>
<h2> Form Validation Example</h2>
<p><span class="error">* required field.</span></p>
<form method="post" action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]);?>">
Name: <input type="text" name="username">
<span class="error">* <?php echo $usernameErr;?></span>
<br><br>
E-mail: <input type="text" name="email">
<span class="error">* <?php echo $emailErr;?></span>
<br><br>
info: <input type="text" name="info">
<span class="error"><?php echo $infoErr;?></span>
<br><br>
<input type="submit" name="submit" value="Submit">
</form>
<?php
echo "<h2>Output Print:</h2>";
echo $username;
echo "<br>";
echo $email;
echo "<br>";
echo $info;
echo "<br>";
?>
</body>
</html>
Output Print
Required fields highlighted
