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Mwamitovi/10_users.php

Created January 29, 2025 06:33
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  1. Mwamitovi created this gist Jan 29, 2025.
    329 changes: 329 additions & 0 deletions 10_users.php
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    <?php
    // Chapter-10: Exercises

    // Question-1

    // 1. Make a web page that uses a cookie to keep track of how many times a user has viewed the page.
    // The first time a particular user looks at the page, it should print something like “Number of views: 1.”
    // The second time the user looks at the page, it should print “Number of views: 2,” and so on.

    // Answer-1
    $view_count = 1 + ($_COOKIE['view_count'] ?? 0);
    setcookie('view_count', $view_count);
    print "<p>Hi! Number of times you've viewed this page: $view_count.</p>";

    // Question-2

    // 2. Modify the web page from the first exercise so that it prints out a special message on the 5th, 10th,
    // and 15th times the user looks at the page. Also modify it so that on the 20th time the user looks at the page,
    // it deletes the cookie and the page count starts over.

    // Answer-2

    $view_count = 1 + ($_COOKIE['view_count'] ?? 0);
    if ($view_count == 20) {
    // An empty value for setcookie() removes the cookie
    setcookie(
    'view_count',
    ''
    );
    $msg = "<p>Time to start over.</p>";
    } else {
    setcookie('view_count', $view_count);
    $msg = "<p>Hi! Number of times you've viewed this page: $view_count.</p>";
    if ($view_count == 5) {
    $msg .= "<p>This is your fifth visit.</p>";
    } elseif ($view_count == 10) {
    $msg .= "<p>This is your tenth visit. You must like this page.</p>";
    } elseif ($view_count == 15) {
    $msg .= "<p>This is your fifteenth visit. " .
    "Don't you have anything else to do?</p>";
    }
    }
    print $msg;

    // Question-3

    // 3. Write a PHP program that displays a form for a user to pick his favorite color from a list of colors.
    // Make another page whose background color is set to the color that the user picks in the form.
    // Store the color value in $_SESSION so that both pages can access it.

    // Answer-3

    // The color-picking page:
    // Start sessions first thing so we can use $_SESSION freely later
    session_start();
    // Load the form helper class
    require 'FormHelper.php';
    $colors = array(
    'ff0000' => 'Red',
    'ffa500' => 'Orange',
    'ffffff' => 'Yellow',
    '008000' => 'Green',
    '0000ff' => 'Blue',
    '4b0082' => 'Indigo',
    '663399' => 'Rebecca Purple'
    );
    // The main page logic:
    // - If the form is submitted, validate and then process or redisplay
    // - If it's not submitted, display
    if ($_SERVER['REQUEST_METHOD'] == 'POST') {
    // If validate_form() returns errors, pass them to show_form()
    list($errors, $input) = validate_form();
    if ($errors) {
    show_form($errors);
    } else {
    // The submitted data is valid, so process it
    process_form($input);
    }
    } else {
    // The form wasn't submitted, so display
    show_form();
    }
    function show_form($errors = array())
    {
    global $colors;
    // Set up the $form object with proper defaults
    $form = new FormHelper();
    // All the HTML and form display is in a separate file for clarity
    include 'color-form.php';
    }
    function validate_form()
    {
    $input = array();
    $errors = array();
    // color must be a valid color
    $input['color'] = $_POST['color'] ?? '';
    if (!array_key_exists($input['color'], $GLOBALS['colors'])) {
    $errors[] = 'Please select a valid color.';
    }
    return array($errors, $input);
    }

    function process_form($input)
    {
    global $colors;
    $_SESSION['background_color'] = $input['color'];
    print '<p>Your color has been set.</p>';
    }

    // The code relies on the FormHelper.php file discussed in Chapter 7.
    // The color-form.php file referenced, which displays the form HTML, contains: ?>
    <form method="POST" action="<?= $form->encode($_SERVER['PHP_SELF']) ?>">
    <table>
    <?php if ($errors) { ?>
    <tr>
    <td>You need to correct the following errors:</td>
    <td>
    <ul>
    <?php foreach ($errors as $error) { ?>
    <li><?= $form->encode($error) ?></li>
    <?php } ?>
    </ul>
    </td>
    <?php } ?>
    <tr>
    <td>Favorite Color:</td>
    <td><?= $form->select($colors, ['name' => 'color']) ?></td>
    </tr>
    <tr>
    <td colspan="2" align="center">
    <?= $form->input('submit', [
    'name' => 'set',
    'value' => 'Set Color'
    ]) ?>
    </td>
    </tr>
    </table>
    <?php

    // The page with background color set:

    // Start sessions first thing so we can use $_SESSION freely later
    session_start();
    ?>
    <html>

    <head>
    <title>Background Color Example</title>

    <body style="background-color:<?= $_SESSION['background_color'] ?>">
    <p>What color did you pick?</p>
    </body>

    </html><?php


    // Question-4

    // 4. Write a PHP program that displays an order form. The order form should list six products.
    // Next to each product name there should be a text box into which a user can enter how many of
    // that product she wants to order.
    // When the form is submitted, the submitted form data should be saved into the session.
    // Make another page that displays the contents of the saved order, a link back to the order form page,
    // and a Check Out button. If the link back to the order form page is clicked, the order form page should be
    // displayed with the saved order quantities from the session in the text boxes.
    // When the Check Out button is clicked, the order should be cleared from the session.

    // Answer-4

    // The ordering page:
    session_start();
    // This assumes FormHelper.php is in the same directory as this file.
    require 'FormHelper.php';
    // Set up the array of choices in the select menu.
    // This is needed in display_form(), validate_form(),
    // and process_form(), so it is declared in the global scope.
    $products = [
    'cuke' => 'Braised Sea Cucumber',
    'stomach' => "Sauteed Pig's Stomach",
    'tripe' => 'Sauteed Tripe with Wine Sauce',
    'taro' => 'Stewed Pork with Taro',
    'giblets' => 'Baked Giblets with Salt',
    'abalone' => 'Abalone with Marrow and Duck Feet'
    ];
    // The main page logic:
    // - If the form is submitted, validate and then process or redisplay
    // - If it's not submitted, display
    if ($_SERVER['REQUEST_METHOD'] == 'POST') {
    // If validate_form() returns errors, pass them to show_form()
    list($errors, $input) = validate_form2();
    if ($errors) {
    show_form($errors);
    } else {
    // The submitted data is valid, so process it
    process_form2($input);
    }
    } else {
    // The form wasn't submitted, so display
    show_form2();
    }

    function show_form2($errors = array())
    {
    global $products;
    $defaults = array();
    // Start out with 0 as a default
    foreach ($products as $code => $label) {
    $defaults["quantity_$code"] = 0;
    }
    // If quantities are in the session, use those
    if (isset($_SESSION['quantities'])) {
    foreach ($_SESSION['quantities'] as $field => $quantity) {
    $defaults[$field] = $quantity;
    }
    }
    $form = new FormHelper($defaults);
    // All the HTML and form display is in a separate file for clarity
    include 'order-form.php';
    }

    function validate_form2()
    {
    global $products;
    $input = array();
    $errors = array();
    // For each quantity box, make sure the value is
    // a valid integer >= 0
    foreach ($products as $code => $name) {
    $field = "quantity_$code";
    $input[$field] = filter_input(
    INPUT_POST,
    $field,
    FILTER_VALIDATE_INT,
    ['options' => ['min_range' => 0]]
    );
    if (is_null($input[$field]) || ($input[$field] === false)) {
    $errors[] = "Please enter a valid quantity for $name.";
    }
    }
    return array($errors, $input);
    }

    function process_form2($input)
    {
    $_SESSION['quantities'] = $input;
    print "Thank you for your order.";
    }

    // The code relies on the FormHelper.php file discussed in Chapter 7.
    // The order-form.php file referenced, which displays the form HTML, contains: ?>
    <form method="POST" action="<?= $form->encode($_SERVER['PHP_SELF']) ?>">
    <table>
    <?php if ($errors) { ?>
    <tr>
    <td>You need to correct the following errors:</td>
    <td>
    <ul>
    <?php foreach ($errors as $error) { ?>
    <li><?= $form->encode($error) ?></li>
    <?php } ?>
    </ul>
    </td>
    <?php } ?>
    <tr>
    <th>Product</th>
    <td>Quantity</td>
    </tr>
    <?php foreach ($products as $code => $name) { ?>
    <tr>
    <td><?= htmlentities($name) ?>:</td>
    <td><?= $form->input('text', ['name' => "quantity_$code"]) ?></td>
    </tr>
    <?php } ?>
    <tr>
    <td colspan="2" align="center"><?= $form->input('submit', ['value' => 'Order']) ?>
    </td>
    </tr>
    </table>
    </form><?php

    // The checkout page:
    session_start();
    // The same products from the order page

    $products = [
    'cuke' => 'Braised Sea Cucumber',
    'stomach' => "Sauteed Pig's Stomach",
    'tripe' => 'Sauteed Tripe with Wine Sauce',
    'taro' => 'Stewed Pork with Taro',
    'giblets' => 'Baked Giblets with Salt',
    'abalone' => 'Abalone with Marrow and Duck Feet'
    ];
    // Simplified main page logic without form validation
    if ($_SERVER['REQUEST_METHOD'] == 'POST') {
    process_form3();
    } else {
    // The form wasn't submitted, so display
    show_form3();
    }
    function show_form3()
    {
    global $products;
    // The "form" is just a single submit button, so we won't use
    // FormHelper and just inline all the HTML here
    if (isset($_SESSION['quantities']) && (count($_SESSION['quantities']) > 0)) {
    print "<p>Your order:</p><ul>";
    foreach ($_SESSION['quantities'] as $field => $amount) {
    list($junk, $code) = explode('_', $field);
    $product = $products[$code];
    print "<li>$amount $product</li>";
    }
    print "</ul>";
    print '<form method="POST" action=' .
    htmlentities($_SERVER['PHP_SELF']) . '>';
    print '<input type="submit" value="Check Out" />';
    print '</form>';
    } else {
    print "<p>You don't have a saved order.</p>";
    }
    // This assumes the order form page is saved as "order.php"
    print '<a href="order.php">Return to Order page</a>';
    }

    function process_form3()
    {
    // This removes the data from the session
    unset($_SESSION['quantities']);
    print "<p>Thanks for your order.</p>";
    }