Topic: PHP Basics – Part 6 of 10: Forms and User Input Handling

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1. Introduction to Forms in PHP

• Forms are the primary way to collect data from users.

• PHP interacts with HTML forms to receive and process user input.

• Two main methods to send data:

* GET: Data is appended in the URL (visible).
* POST: Data is sent in the request body (more secure).

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2. Creating a Basic HTML Form

<form action="process.php" method="post">
  Name: <input type="text" name="username"><br>
  Email: <input type="email" name="email"><br>
  <input type="submit" value="Submit">
</form>

• action defines where the form data will be sent.

• method can be GET or POST.

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3. Accessing Form Data in PHP

<?php
$name = $_POST['username'];
$email = $_POST['email'];

echo "Welcome $name! Your email is $email.";
?>

• $_GET and $_POST are superglobals that access data sent by the form.

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4. Validating Form Input

Validation ensures data is clean and in the expected format before processing.

<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
  $name = trim($_POST["username"]);
  
  if (empty($name)) {
    echo "Name is required";
  } else {
    echo "Hello, $name";
  }
}
?>

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5. Sanitizing User Input

• Prevent malicious input (e.g., HTML/JavaScript code).

$name = htmlspecialchars($_POST["username"]);

• This function converts special characters to HTML entities.

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6. Self-processing Form Example

<form method="post" action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?>">
  Name: <input type="text" name="username"><br>
  <input type="submit">
</form>

<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
  $name = htmlspecialchars($_POST["username"]);
  echo "Welcome, $name";
}
?>

• Using $_SERVER["PHP_SELF"] allows the form to submit to the same file.

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7. Using the GET Method

<form action="search.php" method="get">
  Search: <input type="text" name="query">
  <input type="submit">
</form>

• Data is visible in the URL: search.php?query=value

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8. File Upload with Forms

<form action="upload.php" method="post" enctype="multipart/form-data">
  Select file: <input type="file" name="myfile">
  <input type="submit" value="Upload">
</form>

• Use enctype="multipart/form-data" to upload files.

<?php
if ($_FILES["myfile"]["error"] == 0) {
  move_uploaded_file($_FILES["myfile"]["tmp_name"], "uploads/" . $_FILES["myfile"]["name"]);
  echo "File uploaded!";
}
?>

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9. Summary

• PHP handles user input through forms using the GET and POST methods.

• Always validate and sanitize input to prevent security issues.

• Forms are foundational for login systems, search bars, contact pages, and file uploads.

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Exercise

• Create a form that asks for name, age, and email, and then displays a formatted message with validation and sanitization.

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#PHP #Forms #UserInput #POST #GET #PHPTutorial

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