Form Validationپشتڕاستکردنەوەی فۆرم

<form method="post" action="register.php">
  Name: <input type="text" name="name" required>
  E-mail: <input type="email" name="email" required>
  <input type="submit" value="Register">
</form>

<?php
if (isset($_POST["submit"])) {
    if (empty($_POST["name"])) {
        echo "Name is required<br>";
    } elseif (empty($_POST["email"])) {
        echo "Email is required<br>";
    } elseif (empty($_POST["website"])) {
        echo "Website is required<br>";
    } elseif (empty($_POST["comment"])) {
        echo "Please enter your comment<br>";
    } elseif (empty($_POST["gender"])) {
        echo "Gender is required<br>";
    } else {
        $name    = $_POST["name"];
        $email   = $_POST["email"];
        $website = $_POST["website"];
        $comment = $_POST["comment"];
        $gender  = $_POST["gender"];

        echo "Your inputs are: " . htmlspecialchars("$name, $email, $website, $comment, $gender");
    }
}
?>

<?php
echo "<pre>";
var_dump(empty(""));          // nothing typed
var_dump(empty("0"));         // the user typed 0
var_dump(empty("   "));       // the user typed only spaces
var_dump(trim("   ") === ""); // trim first, then compare
var_dump(trim("0") === "");   // "0" is a real answer

<?php
$errors = [];

if ($_SERVER["REQUEST_METHOD"] === "POST") {
    $name    = trim($_POST["name"] ?? "");
    $email   = trim($_POST["email"] ?? "");
    $comment = trim($_POST["comment"] ?? "");
    $gender  = $_POST["gender"] ?? "";

    if ($name === "") {
        $errors[] = "Name is required.";
    }
    if ($email === "") {
        $errors[] = "Email is required.";
    }
    if ($comment === "") {
        $errors[] = "Please enter your comment.";
    }
    if ($gender === "") {
        $errors[] = "Gender is required.";
    }

    if (count($errors) > 0) {
        echo "<ul>";
        foreach ($errors as $error) {
            echo "<li>$error</li>";
        }
        echo "</ul>";
    } else {
        echo "Thank you, " . htmlspecialchars($name) . "!";
    }
}
?>

<form action="#" method="post">
<select name="Color">
<option value="Red">Red</option>
<option value="Green">Green</option>
<option value="Blue">Blue</option>
<option value="Pink">Pink</option>
<option value="Yellow">Yellow</option>
</select>
<input type="submit" name="submit" value="Get Selected Values" />
</form>
<?php
if(isset($_POST['submit'])){
$selected_val = $_POST['Color'];  // Storing Selected Value In Variable
echo "You have selected :" .$selected_val;  // Displaying Selected Value
}
?>

<?php
$gender = "";
$genderErr = "";

if (isset($_POST["submit"])) {
    if (empty($_POST["gender"])) {
        $genderErr = "Gender is required";
    } else {
        $gender = $_POST["gender"];
    }
}
?>
<form method="post" action="">
  Gender:
  <input type="radio" name="gender" value="female">Female
  <input type="radio" name="gender" value="male">Male
  <span class="error">* <?php echo $genderErr; ?></span>
  <br><br>
  <input type="submit" name="submit" value="Submit">
</form>

<form method="post" action="">
  <input type="checkbox" name="formWheelchair" value="Yes"> I need wheelchair access
  <input type="submit" name="formSubmit" value="Submit">
</form>

<?php
if (isset($_POST["formSubmit"])) {
    if (isset($_POST["formWheelchair"]) && $_POST["formWheelchair"] == "Yes") {
        echo "Need wheelchair access.";
    } else {
        echo "Do not need wheelchair access.";
    }
}
?>

<?php
echo "<pre>";
$username = "Hana";
$kurdish  = "هانا";
$email    = "hana@example.com";

var_dump(strlen($username));      // 4 letters, 4 bytes
var_dump(strlen($kurdish));       // 4 letters, but 8 bytes!
var_dump(mb_strlen($kurdish));    // 4 characters

var_dump(str_contains($email, "@"));                // true
var_dump(preg_match('/[0-9]/', "rezan7"));          // 1 = a digit was found
var_dump(preg_match('/[0-9]/', "rezan"));           // 0 = no digit
var_dump(filter_var("hana@example.com", FILTER_VALIDATE_EMAIL));
var_dump(filter_var("a.@", FILTER_VALIDATE_EMAIL));

<?php
$username = "";
$email = "";
$errors = ["username" => "", "email" => "", "password" => ""];
$success = "";

if ($_SERVER["REQUEST_METHOD"] === "POST") {
    $username = trim($_POST["username"] ?? "");
    $email    = trim($_POST["email"] ?? "");
    $password = $_POST["password"] ?? "";

    // 1. Username: required, and no digits at all
    if ($username === "") {
        $errors["username"] = "Username is required.";
    } elseif (preg_match('/[0-9]/', $username)) {
        $errors["username"] = "Username must not contain numbers.";
    }

    // 2. Email: required, must contain @ and a dot, and must be a valid address
    if ($email === "") {
        $errors["email"] = "Email is required.";
    } elseif (!str_contains($email, "@") || !str_contains($email, ".")) {
        $errors["email"] = "Email must contain @ and a dot.";
    } elseif (filter_var($email, FILTER_VALIDATE_EMAIL) === false) {
        $errors["email"] = "Email is not a valid address.";
    }

    // 3. Password: 8-20 characters, and mixed (letters AND digits)
    $length = mb_strlen($password);
    if ($length < 8 || $length > 20) {
        $errors["password"] = "Password must be 8 to 20 characters.";
    } elseif (!preg_match('/[a-zA-Z]/', $password) || !preg_match('/[0-9]/', $password)) {
        $errors["password"] = "Password must mix letters and numbers.";
    }

    if ($errors["username"] === "" && $errors["email"] === "" && $errors["password"] === "") {
        $success = "Registration data is valid. Welcome, " . htmlspecialchars($username) . "!";
    }
}
?>
<form method="post" action="">
  Username: <input type="text" name="username" value="<?php echo htmlspecialchars($username); ?>">
  <span class="error"><?php echo $errors["username"]; ?></span><br>
  Email: <input type="text" name="email" value="<?php echo htmlspecialchars($email); ?>">
  <span class="error"><?php echo $errors["email"]; ?></span><br>
  Password: <input type="password" name="password">
  <span class="error"><?php echo $errors["password"]; ?></span><br>
  <input type="submit" value="Register">
</form>
<p><?php echo $success; ?></p>